Status_203 - 11:29 am on Nov 11, 2009 (gmt 0)

Firstly, just speculation but I would expect the search engines to be able to identify a inbound link profile made up mainly of profile links.

Secondly, the PR of the homepage is irrelevant. What is the PR of a profile page a few days/weeks/months old? Are the profiles actually crawlable? Are the links nofollowed?

Finally, and many here would disagree with me on this one, I wouldn't do it because it is in no way adding value to the web (as opposed to the established method of contributing *quality* posts with a link in your signature).