[getsat]

I know they were profitable (heard from Twitter employees during lunch) in very late 2009 right after Bing and Google decided to pay them tens of millions of dollars each month for access to realtime Tweet data. They only had ~150 or so employees at the time.

No idea if they're still profitable, and the Google deal has since been canceled.

[veyron]

Does Bing still pay for access to the data?

[getsat]

No clue, sorry.

I imagine Google didn't bother renewing because they're hoping to get interesting data from Google+ users.