Google introduced rich media ads recently, few advertisers have participated in this new experience. Some screenshots have been posted recently concerning Video Ads by Google such this one :
videoads.jpg
Videos as usual have the mention Ads by Google, with the pause/play and volume control. Then by clicking on the video you’ll be redirected to the advertiser website. I didn’t see any real ads working to comment more on the technical aspect, but I think after launching Google Video, Google have more control on videos now and I think the service will be great for advertisers and publishers too.