If people use accurate financial valuation methods, the EV may be less than 100B. However, I just tried to imagine the economics impact if they shut down FB. Then, what do you think?

I am sharpening my knives, can not wait to short this crap shit, at this valuation.
And if investors drive the price higher still, I shall increase my short positions 100% on every 25% price rise.

Profitability and A view for the future. Yes, facebook is worth 100billion. Unless its users realize that it isnt worth a penny!

$100 billion ...
The capitalization of a company should be the sum of:
* all present assets (and liabilities)
* all futures assets (and liabilities) discounted to today
* all expected future cashflow profits discounted to today
In Facebook's case, for the sake of simplicity, it can be assumed that assets (and liabilities) can be neglected. Thus the capitalization is the value of all expected futures cashflows discounted to today.
If Facebook had 500 million paying users, is it plausible that on average for each user (in the lifetime of his account) Facebook can create a total profit worth $200 today?
Assuming Facebook has a 50% profit margin, then the present value of all cashflows with each user will have to be $400.
Let's say a user is on average an active payer for 4 years.
Thus the present value of cashflows for the average user per paying year is $100.
Is the sum of advertiser money given to FB per user per year and direct user generated payments per year equal to (present value) $100?
Assuming only advertising money, and that an advertiser spents 10 cents to generate $1 of revenue, will a FB user spend $1000 because of ads seen in FB? Unlikely ...
Assuming only direct user payments to FB, will a FB user pay $100 to FB per year for services? Not at the moment, maybe in the future, but is that sustainable considering internet competition (google+)?
Reduce all numbers by a factor of 10, and it becomes plausible, otherwise the $100 billion does not seem sustainable.
If FB plans on becoming a mobile phone carrier and cell phone manufacturer then it is very plausible that it could charge at least $100 per year per user for the FB service. It certainly will have multiple capitalizations to be a telecom giant ... but that is not the FB model, their model is making nice webpages.

Facebook may be doing well.......but i think this current valuation of around a 100 Billion Dollars is way too much.....furthermore Adrew ross Sorkin very rightly pointed out the fact that the definition of a user is pretty vaguely defined in their IPO prospectus.....anyway the bottom line is that this estimate is ludicrous by all standards

Facebook is in a business that has a history of creative distruction and though they have built and awesome user base, you never know what will come along that bests Facebook. As well, there will be more scruitiny of the privacy that facebook invades.
Having said that, facebook should go out with a PE of Google not of Apple and Facebook will be subject to business cycles with advertisers cutting back in down business cycles.

I have just deleted my Facebook account, because it has become a great risk. Facebook builds your professional, sexual, political etc profiles and this information is sold without your consent. With timeline, these profile will depict your evolution and history in this respect. I believe they will replace most other mechanisms of evaluation, such as job interviews and will introduce great discrimination against atypical people. Wherever a choice is to be made, school applications, jobs, flats, etc. a Facebook screening will be applied and whoever fits will be favoured ... if you do not want to be treated this way, you need to opt out today.

With almost a billion users facebook could charge a minimum service fee from users and a big portion from advertisers.

Facebook is a death knell for each one of us. $100 billion my foot!

The real valuation of Facebook can only be evaluated when we know what percentage of users are willing to share their information with companies.

Facebook is a fad. It does nothing to nurture the spirit.

This stock will skyrocket quickly out of the gate due to all of the hype and media coverage creating enormous demand. Then it will come crashing back down to earth just like most hot issues before it. The people who will make money are the big wall street firms and the insiders who are already subscribed to the stock. Don't believe me - just call up your broker and tell them you want some allocated shares prior to the launch. Best of Luck!

Are Facebook users willing to supplying personal information for free indefinitely?

Facebook does have benefit to people around the world, but the true thing is that it makes people less networking by face-in-face. Everyone is like a robot, sitting in front of their computer or lap top typing words. I guess there is no physical networking between people any more after they using facebook to communicate to each others.

Out of 800 mil, how many are 12 year olds, like my daughter, and how many barely use it, like myself?

I wouldn't touch FB stock with 10 foot pole, at least not at its valuation of $100B. There is just too much hype for someting we can live without. If it disappeared tomorrow, there will be some discomfort for some people for a few days but life will go on as normal.

A) Ads are junk, I never click them, nor will I - didn't do it elsewhere, why is FB any different.
B) Scale: You can't target ads - you can't share that data with advertisers, you can't use the relationship people had to target with ads - so what advantage is FB touting?
C) Social media fatigue - this is a communication stream like email, twitter, IM... don't think its anything more. Once too many of the wrong people start using FB - like stalkers, hackers, generally people in real life you want to avoid, like that annoying person in high school who keeps pinging you... close the browser.
D) Lack of income - advertising income takes you so far, then it collapses when the one trick pony is over.

I see a bubble. I've never clicked on any ads on FB and I try not to share too much info about me, which is a trend perhaps amongst people my age (in my 30s) and older. I won't use it to login to other sites because I feel it makes it unsafe. Most people I know do the same and are growing more concerned about privacy on the internet.

Frankly, I think our idea of valuation is deeply flawed. The true value of a company has to be gauged as to whether a shutdown of the said company will result in major disruptions to the way business is conducted. By this test, Microsoft's valuation is justified (most businesses still run on their products) as are the valuations of other corporations such as Procter and Gamble, Johnson and Johnson which manufacture a variety of essential products and major electric utilities such as National Grid PLC (we would have no electricity without them). On the other hand, the consequences of Facebook shutting down would be several million irate individuals who, after a day (maybe a week) of griping about the shutdown will soon forget about it and find new ways to connect with each other through other social media sites (i.e. Twitter and Google Circles). Facebook is definitely not worth the $100 billion just as subprime mortgage-backed securities were not worth the AAA ratings that were handed out by the bond agencies before the crash of 2008

It's worth that and more. I am 28. Many of my friends in their early 20s have built their entire social presence through this site. Not only does it act and communication tool, it defines who they are, what they like, who they like, where they've been. So many of these users are living through the site.

If the site came down next week, I think a lot of people would struggle to deal with a Facebook free world. It would be like bringing down the cellular phone network and telling people they had to actually arrange to meet somewhere at x time. If they don't show up, that's it.

So, is it valuable? Yes. In fact, it's almost priceless. It's no longer about pure profit. This site is part of modern society.