As far as I can tell, Google posted this message without being forced to by any government. Most companies would keep this kind of thing quiet, or lie about it, especially if privacy advocates got wind of it. Google, within a few days of finding out about the issue, posts an APOLOGY for doing something that MIGHT have possibly damaged a few people, IF the information they collected had been leaked.
Unless we have reason to believe otherwise, Google screwed up, and as soon as they were aware of the mistake, took steps to rectify it and then went public about the mistake. If we get evidence that Google is lying about this, that's another story, but has there been any such evidence yet? I'm all for raking corporations over the coals when they make mistakes and don't own up, but how often do you see a giant corporation blurting out "mea culpa" like this?
Also:
As much as I like Google I hope they get the book thrown at them over this. To claim that they have accidently been collecting this data for three years is just silly.
It's not remotely silly. A week ago I discovered a DB table at my (multinational media conglomerate) company that had been silently logging data for -- wait for it -- three years. It wasn't any personal info, or data we needed, but everyone had forgotten about it. The idea of Google making a similar mistake is not "silly" at all.