I still enjoy the game quite a bit, but I'd much rather just pay the 99 cents than burn 45 seconds every 5 minutes to watch an ad.
If we assume an average revenue of $1.05 per copy ($1.50 minus Apple’s 30% cut) and 6.5 million sold copies in nine months their revenue would be about three quarters of a million per month.
The above linked TechCrunch article has a seemingly more recent but unsourced number of twelve million copies sold. That would put the revenue at about one million per month.
I’m not sure how accurate that estimate is, though. They sold a million copies of their Halloween version in only six days [2], that’s quite a bit more. (If I remember correctly there was no free version of the Halloween special.)
[1] http://mobilewebgo.com/how-did-angry-birds-become-blockbuste...
[2] http://www.rovio.com/index.php?mact=Blogs,cntnt01,showentry,...
We shall see indeed: "By end of year, we project earnings of over $1 million per month with the ad-supported version of Angry Birds" http://techcrunch.com/2010/12/03/angry-birds-android-1-milli...