Michael Mazel over at Google just sent me a link to this happy publisher carrying AdSense ads case history he wrote up. In it the folks at InfoPlease reveal they are making more with Google AdSense ads than they were as members of general online ad networks. https://www.google.com/adsense/infoplease
Which is fine... but you should realize general online ad networks have been paying diddlysquat for ages now, so anything is better than that.
I've been asking around about the profitability of AdSense ads and heard very different stories -- ranging from under $1 CPM to $20CPM for publishers. I've also heard some folks say the ads are amazingly well targeted to their niche, and others say the opposite (such as an ad for healthcare pros that appeared on a kid's site.)
So the jury is still out. I think we're all hoping the kinks work out and this is a great program in the long run. In the meantime, email me your experiences! AHolland@MarketingSherpa.com