A DigitalPoint Forums thread notes that Google AdSense has added a new ad unit. The new ad unit is 200x200 pixels, which was most likely a much requested size.
If you login to the AdSense console, you should see a message on the top right that reads;
NEW We've added one additional format for your text, image, and video ad units. Learn more...
When I tested the "Learn more..." link above at the time I wrote this, it took me to a page that read;
We're sorry, but the information you've requested cannot be found.
Here is a live AdSense ad:
Forum discussion at DigitalPoint Forums.
This article was written the night before, and scheduled to go live at this time.