Adwords & Adsense – CPM changes?

So Google launched site targetting a few days ago.
I have both an adwords and an adsense account with Google, or more precisely, the company has one of each and I have an adsense account as well 🙂
From an advertiser’s perspective I would have thought that selecting a range of sites would have led to impressions clocking up, but I was obviously wrong.
With the standard adwords you are given an indication of where your ad will appear in relation to the amount you bid on the keyword or phrase, whereas with the CPM model you don’t seem to have that option. Some kind of “bid X to get Y impressions on somesite.tld” would be helpful. Maybe this kind of functionality is going to be added at a later stage.
The flipside to this is adsense.
How will earnings be affected by the new payment model?
If advertisers were previously paying for clicks does this mean that now publishers will be paid for impressions?
There doesn’t seem to be any mention of it in the adsense help docs. Am I missing something?