Welcome to WebmasterWorld Guest from 188.8.131.52
Forum Moderators: open
I assume that part of the reason for Google's occasional click tracking is to find how far users have to dig through the results to find what they're looking for. That would produce nice comparisons over time.
If they find that the top ranking sites are doing so without guestbook links, then they tweak and re-run.
Its the only way to be sure.