The ad platform for facebook will be awesome, I can't wait to get in there and see the data. This will allow for so many more placements of ads on Facebook, MySpace needs to create something similar, for their ad center is only a form you fill out, although the ads can be connected in with third party tools...Behavioral and targeting analytics -- coming soon from Facebook
I think the main page is far too cluttered and the site has difficulty developing and managing the search community (there's not many ways to connect with others). I wonder if it will last. I think Mahalo could only be used for SEM, I don't see how it will become as powerful as Google for the end-searcher - There's no technology to back it up.