We launched a new firefox extension which intergrates PostRank into GoogleReader. Would love to hear some feedback. First come, first serve invites: http://gr.aiderss.com/?ycomb

I just began working on a very similar idea :) anyway, how do you score the posts, using bayesian filtering?

Not quite, it's more of a customized statistical function at this point -- Postrank. We're working on a whitepaper which will delve into the internals..