(disclaimer: i totally miss the old school socialmoth.com and the community without any facebook - but if fb is where it's at, then fb is where it's at. i was the one who posted a couple times that i was glad you put ads on sm - i REALLY like the site / concept)
it seems (at first glance) that the facebook app has less comments / conversations based on posts than the main domain - is this something you've seen from an aggregate perspective?
otherwise, it seemed (from a user's perspective) that sm had this core set of users in the beginning - i read about it on techcrunch, etc. and then when the facebook app came out - all hell broke loose (not to mention "love inflation"). I'm guessing facebook caused a near-exponential spike in users?
also - props on overhear.us - looking forward to enjoying it as well.