The BBC has just put up a story with musings on why Microsoft paid $240m for a mere 1.6% stake in Facebook.

You can read that here

The only one I agree with is the last point. Facebook is worth that much because Microsoft says so. And they made this move purely to counter Google, who already have the lion's share of the web advertising market.

But here are some reasons Facebook isn't (or shouldn't be) worth $15bn

1. Pirates, Vampires and other really stupid applications

Actually the Beeb cited this as a good thing about Facebook. I hate these applications. They are stupid. And because of the way Facebook is set up to invite every friend you have to use the application when you install it, I get about twenty of these every day.

2. The massive growth in users may be short lived

I admit I am no economist, but those 50 zillion users who joined Facebook in the last year are not necessarily going be be 'loyal customers' in the future. Steve Balmer may be right, Facebook could be a fad, and people will move onto the next big thing in 2008.

3. Nobody clicks on adverts anyway

Any company is worth as much as its revenue, either current or projected. Facebook currently have zero forms of revenue other than advertising, either traditional banners or sponsored surveys, without the benefit of being able to easily tailor advertising for the content of the page. Oh and those stupid virtual gifts. It's hard to think how they could come up with additioal revenue streams.

4. The FriendsReunited problem

FriendsReunited was like Facebook v0.8 Alpha. When it first appeared, there was a rush of people joining, all desperate to find out what their old flame from school looked like now, etc. But once you have joined Facebook, added everyone you remember from the old days to your friends list, what is left to do? After not seeing someone for ten years or more, you most likely don't have a lot to talk about, you do the typical exchange of wall posts, comparing size of family and career success, but usually they may as well not be on your friends list, share little in common with you now and they definitely won't be interested in your daily status updates.

5. Privacy

It hit mainstream news headlines over the summer, but Facebook's default privacy options leave your photos and personal details open for the world to see. You have to turn on privacy rather than turn it off. It's made more complicated that you may have set your details as private, but those in your network can still view them. Why not just have security at maximum by default, so it's your decision to share your personal details rather than having to hide them?

So really, this $15B valuation says more about Microsoft's desire to prevent Google from capturing more of the advertising market than it does about the real value of Facebook.