That's what Scarecrow did. Basically Google said (in tricky wording) that they wouldn't be using the data from it's different services (ie. Gmail) as one. Now they say that they will. So now in theory the Government could subpoena- Your emails, your usage stats, what terms you have searched for, what sites you went to, what IP addresses you used, how much you spend on Adwords, how much you make on adsense, what news topics you read etc... They could do this in the past of course but now Google is saying that it has no problem clicking the pieces together as it where.