Google seems to be testing a new AdWords Extension, one that has not really been seen or talked about before, from what I can tell.
These are search ad extensions, basically search boxes in the ad, that let you refine your search to results within the site listed in the ad only. Also known as a site search.
Here is a picture of the site search ad extension:
I spotted this via the WebmasterWorld forums where advertiser jebernier posted a screen shot and then was told by his AdWords representative that his was a beta test being run by Google.
Do you like them?
Forum discussion at WebmasterWorld.