In response to my article on using RSS for SEO, the question has arisen of whether outbound links from a web page really reduce its PageRank. The answer? Yes and no.
Without going into too much detail, Google doesn't take PageRank away from one page and give it to another, so the answer is no. But it does allocate a page's PageRank voting power between all of the pages to which it links. So if your web pages link to each other, and not to external pages, then all of your pages' voting power goes into increasing the PageRank of your own pages, rather than some of it going to increasing someone else's PageRank. So the answer is also yes.
If you do a Google search and check the PageRank of the pages that come up in the results, you'll quickly see that pages can appear higher in the results than pages with higher PageRank. Why? Because Google considers them to be more relevant to the search query. (Freshness may also factor in.) It has been suggested that Google may rate a page's relevance to a topic higher if it links to pages they consider authoritative on that topic. If this is true, it may very well be worth letting a little PageRank leak off to such sites in return for the increased relevance.
Returning to the topic of using RSS for SEO, the pages to which most RSS feeds link seem unlikely to be authoritative enough to make the tradeoff worthwhile.