We have a dedicated thread for these sub-topics that Matt touched on:
301 Redirect Means "Some Loss of PageRank" [webmasterworld.com]
Does Page Rank Still Matter? [webmasterworld.com]
I also appreciated Matt's comments about the challenges of "faceted navigation" - different sort orders of the same basic data. He talks about using rel="canonical" and using the "ignore parameter" choices in Webmaster Tools. And he also mentions that some users can get lost with faceted navigation. I agree - it happens to me on Google SERPs when I forget which options I've clicked on!