A WebmasterWorld thread reports that Google is testing placing black borders around AdSense ads without the consent of the publishers.
First reports of this came in at about 1pm (EST) yesterday, where the publisher expressed his distaste.
Many other publishers started to notice this happening on their ads as well.
Google pulled a similar stunt a few months back, testing a new font without the consent of the publisher. The publishers complained about the comic sans font and finally Google removed the AdSense font from those test ads.
The thread is now too long pages long and filled with many complaints. Maybe Google should have people opt in to be their genie pigs from now on?
Forum discussion at WebmasterWorld.