"The other was a curious query, as it trasmitted events(used generic names so I dont know what each stood for), a unique ID, and interestingly enough a variable called “rep”, presumably implying a user reputation level."
It is very unlikely they would store reputation on the client side. I can only applaud the author for healthy amount of justified paranoia, but here he most likely off the mark.
And a lot more - blogger, picasa, google desktop search, google talk and voice, google mobile, docs... I don't see a way to clear cookies in Maps on the iPhone either.
I suspect there's a lot more that they can infer than we would initially think, too. E.g. When you email someone at gmail, your sending ip address and (typically) real name are in the headers - no need to use google checkout to get a lot of probable matches.
It scares me not because I think google are abusing it now, but that it will never be deleted no matter what happens to google management or what government gets in power - in any country they have data replicated - for the rest of our lives. That could be a long time to trust them, and it becomes more powerful the bigger the collection gets and the more we rely on the net.
It is very unlikely they would store reputation on the client side. I can only applaud the author for healthy amount of justified paranoia, but here he most likely off the mark.