Interesting -- I would not have guessed they were storing all our keystrokes. It'd be fascinating to mine that data, for example, to find patterns of typos.
Anyone that has used the multi-user collaborative editing should not be surprised that at the very least your keystrokes are regularly being transmitted to Google for playback on other people's computers. It's not so much of a leap to assume that they are also stored given Google's lust for data.
