The link is everything. If several people you trust as filters, link to the same stuff then it's probably something you should devote some of your precious attention to.
Steve's idea of a sort of 'automated blogosphere triangulation' algorithm is something that I can't wait to try out once he and Dave Sifry finish designing and implementing it.
From RSS for Food:
If you're going to survive cancellation by acting as a filter, you have to be extremely efficient at not duplicating your subscriber's existing knowledge set. You know that feeling you get that you might have seen this episode of Law and Order, and oh, wait, saw it. Not good. At the same time, you want to give page rank to significant posts, both for the enhanced whuffie of the referenced post and so that discovery engines such as Technorati will list your homage in the resulting cosmos.
I usually resolve this conundrum by quoting a relevant and hopefully unique element of the citation, adding a [via] link to the most authoritative reference I am aware of. Dave Winer's Scripting News, Scobleizer, Roland Tanglao, Marc Canter, Doc Searls... if one of them has it covered, I signal the fact so that natural affinity groups recognize they've already consumed the data.