Henry Blodget - Is Facebook worth the $15 billion valuation implied by Microsoft's investment?

Silicon Alley Insider's list of 25 most valuable startups: Facebook #1 at $9 billion

From Silicon Alley Insider:

THE SAI 25: THE WORLD'S MOST VALUABLE STARTUPS
Rank
Company Valuation
1. Facebook $9 billion
2. Wikipedia $7 billion
3. Craigslist $5 billion
4. Betfair $5 billion
5. Mozilla Corp $4 billion
6. Yandex $3 billion
7. Webkinz $2 billion
8. LinkedIn $1.3 billion
9. Habbo $1.25 billion
10. Oanda $1.2 billion
11. Linden Lab $1.1 billion
12. Kayak $1 billion
13. QlikTech $850 million
14. Ning $560 million
15. Slide $550 million
16. TheLadders $500 million
17. Stardoll $450 million
18. Ozon $450 million
19. Thumbplay $400 million
20. Glam Media $400 million
21. Rock You $325 million
22. Tudou $300 million
23. Efficient Frontier $275 million
24. Zazzle $250 million
25. Spot Runner $250 million

Here is a TechCrunch article that explains SAI's logic:

Today, Henry Blodget & Co. at Silicon Alley Insider try to peg valuations on 25 private Web companies. Facebook is at the top of the list, but it is valued at $9 billion instead of the $15 billion that Microsoft’s investment put on the company. Why? Because everyone knows that the $15 billion is too high, so SAI decided to apply a 25X multiple on Facebook’s 2008 revenue forecast of $350 million.