This is obviously a topic which is being done to death at the moment, however I was thinking a bit about what Microsoft might want to do with Facebook in terms of it's technology architecture if they buy into / buy out / (pick your term) Facebook.
Facebook is currently written in PHP. I haven't read anything at all about what else they're using, but lets assume the web server is Apache or something similar, and the backend database is MySQL (google seems to suggest that's the case - if so then it's a pretty impressive endorsement for MySQL).
So if you're Microsoft and you take over a controlling stake in Facebook, what do you do to the technology architecture? None of the existing products in use are Microsoft technologies, and if Facebook becomes Microsoft controlled / owned / (again, pick one) then surely they'd want to get some of their own tech in there for the sake of publicity and marketing.
One of the ways they could go, is to stick with PHP but redeploy using IIS7. One of the interesting things Microsoft has been doing with IIS7 is improving their native support for PHP quite a lot. And talking about it, quite a lot.
I say it's interesting in terms of their strategic direction because I couldn't really see it making much market sense in the smaller picture. Typically people who lean towards the using the 'AMP' portions of the LAMP stack tend to be pretty hung up on that whole first letter, being L for Linux. They tend to be typically anti Microsoft and have tattoos of penguins on their bodies (small ones, and in places which don't really hurt, but still - they're tattoos). These aren't people who are going to run Windows just because IIS7 has much improved PHP support - and so maybe Facebook could be something of a vehicle to wave the flag for PHP on IIS7 / Windows? I'm not sure how many people it would convert, but it would definately help raise awareness of IIS7 as a viable hosting option for PHP developers - that is, assuming it actually works well.
It'd certainly be interesting to monitor various communities in the wake of something like that.