I'm looking through a list of Pligg sites and the ones that are do-follow all seem to use redirect. Here is an example (most definitely not my site): http://www.efixx.com/ When it redirects like that, I assume it gives no link juice and is therefore worthless from an SEO perspective. Other thoughts?
If it's 301 redirect, according to an SEOMoz study you loose 1 to 10% of link-juice, otherwise it's as good as a direct link. Though their studies say that even meta refreshes have the same effect, I wouldn't go with that ;-)