Google is going to reveal today a new link attribute called "nofollow", which site makers can use to classify hyperlinks as not being counted by search engines, in order to make most types of spam useless. A site owner would program links in certain areas to have this text in the link tag:
rel="nofollow"
The link would then not be counted in Google, and presumably other search engines will support the tag.
Interesting solution. More at
InsideGoogle.