Yesterday we reported wide spread reports of Google Trying Google Logo on AdSense Ads. Someone in the forums received a response from Google on the matter.
Thanks for your email - as you've mentioned, the change that you saw was part of ongoing testing to improve our ad formats. Such variations are a normal part of our testing process and generally run for short periods of time only. No permanent changes are planned at this time.
To maintain the integrity of ongoing testing, we do not permit publishers to opt out. However, please rest assured that such variations should impact only a very small percentage of your impressions.
We appreciate your patience and understanding as we work to improve our program.
Stephanie The Google AdSense Team
Two things from this: (1) This is confirmed as a test (2) Even if you hate the way it looks, you cannot opt out
Forum discussion at DigitalPoint Forums.