With Adobe AIR finally released and Flex 2 already out. Not to mention Ruby on Rails starting to make more buzz, along with .ASP NET what are social media / web 2.0 sites being developed in these days. Or is it just dependent on what server it runs on.

Maybe my question should have been what is the dominating framework being used in the developers fields. Anyone know? 

Another thing to consider would be client side user interface libraries... I haven't yet come across anything close to YUI ( the Yahoo User Interface Library).

what do you think of moo.fx