Been using Adsense since right after it was launched, and it has covered the hosting expenses and then some..
(how much is a secret..
)
But the earnings started to drop in 2005-06, probably because it's getting pretty common and people are starting to go "blind" and ignore the ads..
But it's good to see that they're always trying to improve it and add new features, like the (almost) new video ads etc.
And it's also good that they're dropping the "Ads by Gooooooooooooogle" text on the ads now and replacing them with some rather nice graphics text instead.
Looks much better and cleaner now..