We have been reporting about the Google AdSense scam, that rides on the Google name and takes people money, with virtually no return, for a long time now. We first mentioned the Google Money System or Google Kit back in March, and then we blasted Google for allowing AdWords advertisers to advertise for such scams the month after. Finally, Google did something about it by banning these advertisers and then writing about the scam publicly, so people are more aware.
It now seems like these scam artists are taking their business and marketing offline by making cold calls to random businesses. An AdSense publisher posted a thread at Google AdSense Help telling a story that his parents received a phone call from someone claiming to work at Google. The person tried to convince his parents to sign up to Google AdSense. The story is not incredibly clear, since it comes third hand, but it would not surprise me if these scams are making their way to phone scams.
The one thing I should add is that Google has been pushing the AdSense marketing budget a bit. They recently started doing AdSense radio ads to try to help educate people about the product and drive more publishers to use it. So there is a possibility that Google set up a sales team to encourage publishers to use AdSense, via cold calling. But it seems not too likely, in my opinion.
Forum discussion at Google AdSense Help.