Unfortunately for the AACS, it looks like it is going to be quite tricky for Google to take on this measure, considering the 1,000's of websites this processing key has been published on and more showing up all the time. Going by the letter, Google had a week from the letter's date of April 17th to comply and despite that period now being long overdue, Google still indexes 1,000's of website site links containing the key as well as the links indicated for removal in the letter.
The key was made quite public yesterday, and will likely lead to new software or better support for HD DVD in third party software. Despite the legal grey area this is treading in, it doesn't seem to be stopping thousands of people from spreading the word. You can read the actual cease and desist letter here.