I'm not sure why they would. This information seems extremely relevant to Google's line of business.

As far as I know Google tracks with cookies in the standard way. I would be pretty shocked if they were tracking based on anything like fonts or plugins. Is there already evidence to the contrary though?

While I'm not aware of anything it certainly stands to reason that they would, especially with their DoubleClick network.

If the EFF with their limited resources figured this out, Google likely would have, too.

Google and Doubleclick just give you a cookie, though. They don't need to be nefarious.

Google could not feasibly track their user-base this way. The load time for a Flash application that returns font lists (though short) is much longer than they, or their users would tolerate.

Not to mention totally unnecessary. Most people are just fine with cookies.