Google stealthily monitoring clickthroughs from search-results: I noticed this the other day because if you get a 404 on the modified link, you get taken to a Google error page.
There’s some very subtle clickthrough tracking going on at Google. Just before you click on a link on a search-results page, at the “on mousedown” event, Google rewrites the links in its search results with a long redirector URL that is presumably being used to track which search results are being selected most often.
I don’t know why they’d go to such trouble to obscure the tracking, since the blogworld is a small place and it’s gonna get out eventually. How could you conceivably hope to hide something like this? And when it does come out (and it will), you end up looking sneaky.