The Webmaster Tools group has added subscriber counts to the set of tools. This will give you a count of how people are using Google Reader to subscribe to you sites RSS Feeds. Would seem pretty cool, but not super inclusive. Two big problems. Only shows...
Google has announce they have acquired FeedBurner . That will be a huge addition for context aware advertising. Being a FeedBurner subscribe I have noticed they have been slow in get ads into the feeds. I guess this explains why. Congratulations to Feedburner...