A WebmasterWorld thread named made the google_hints grade! discusses a feature in AdSense available by invite only. The feature is named Google Hints, what this allows publishers to do is add keywords in the AdSense code to help Google determine the ads they should be matching on. Obviously this is only by invite only. If anyone can use Google hints, it can be seriously abused.
This is somewhat related to the topic I discussed about a month ago, Should Contextual Ad Networks Use CPC In Ad Placement?
If you trust your publishers, then yes. CPC should be involved and yes Google Hints should be available.
Forum discussion on Google Hints at WebmasterWorld.