In November last year we changed our approach to forum signatures so that members with less than 100 posts had their signature links tagged with the 'no follow' attribute.
The main reason for this was an attempt to curb the volume of people posting meaningless crap on the forum, with the sole purpose of generating back links to their own sites.
Unfortunately this softer approach did not work, so we've been forced to take another step.
As of now, forum signatures are no longer visible to non-logged in users. Including all search engine spiders.
We treasure the quality of this forum and whilst it's an unfortunate step we needed to take, we felt it more important to create a fluff free environment where everyone is here to be a part of the community, rather than acting in their own self interest, than the small amount of link love we could give to members.
Will it mean the end of fluff posting? Probably not -- we are at the top of most lists of "forums to go to and link spam" around the web, so we're sure to still get the odd uninformed practitioner. But our fine team of moderators will be all over it.
I know this will disappoint some, but I hope you can look beyond the Google juice and help bring SitePoint back to a fluff free environment.