I got this announcement from Google via E-Mail yesterday. Sounds like some interesting new options:

Dear AdWords Advertiser,

You have been selected to test Site Targeting a new AdWords feature that will allow you to easily target your ads to specific content sites across the Google Network, giving you a new way to reach people who will find your ads relevant and useful.

The Site Targeting feature consists of the following components:
1. Site Targeting: You can select specific content sites across the Google Network where you would like your ads shown. This lets you connect with people who are likely to be interested in your product or service.
2. Impression-Based Bidding: With site targeting, you set a maximum CPM that is, the maximum price you are willing to pay for every thousand impressions your ad receives on a particular site. Your ads compete for placement on a site with other CPM and CPC ads in Google's auction. Google's approach is different from other CPM models, where advertisers must pay a fixed CPM. On AdWords, you pay no more than the minimum price needed to run an ad on a site.
3. New Ad Formats: In addition to text-based ads and static image ads, you can run animated image ads within your site-targeted campaigns. This is an enhancement to the image ads option we introduced last year. Image ads are carefully evaluated before they are allowed to run on content sites in the Google Network.