I recently posted a question that is related to what you're talking about. Clixgalore claims that their affiliate links will now pass PR (or "link popularity", as they refer to it), but I'm not sure how they do it (which is what I was trying to figure out...)
So you might want to check them out. It's strange, though, because affiliate links have always been re-directs (as far as I know). They say that there will be a "reference" to your site in the link, whatever that means.