They definitely need a "rate this application" feature for QUANTITATIVE parsing of application quality. (the shout-out "wall" reviews are useless). The rating should be prominently places on the app install page so that when you get an invitation you can easily evaluate before installing. Applications below a certain rating threshold should have limits placed on invitations sent out to limit their viral potential (i.e. no more than 5 invites per user sent out instead of 20). Newsfeed and mini-feed event maximums for those applications should also be crippled to limit their viral potential.
I think it was a good bet simply because another loss to Google would have been a death blow to MSFT's online strategy. It's obviously hard to justify the multiple based on what we know now, but I'm willing to bet that MSFT knows more about Facebook's monetization strategy than we all do.
User base numbers need to be looked at as daily or monthly active users. Friendster has tens of millions of dead/inactive accounts, so their 50M number is meaningless. Follow the traffic:
