There's a solid discussion going on over at WebmasterWorld, called Anatomy of an EPC Collapse which has stirred up the great "don't be evil" debate once again.
For those unaware of what EPC means, it's Earnings Per Click - a valid metric in measuring the effectiveness of cost-per-click advertising on publisher's websites.
I've got a couple of zingers in there already and there doesn't seem to be any end in sight. The matter concerns Google's AdSense program and how some publishers have seen EPC collapse while all other metrics - Pageviews, Clickthrough Rate, # of clicks, etc. - rise.
The effect is usually slow growth in overall earnings. For instance, one publisher reports clicks more than doubling when comparing Feb. 2006 to Feb. 2007, but earnings only rising 28%. A linear system would have produced a better-than 100% increase in earnings, but, of course, when dealing with Google's swift algorithms, nothing is linear, or revealed.
Personally, I think Google is FOS, but that's just my opinion.