http://www.google.com/support/webmasters/bin/answer.py?answer=66736 When google says redirecting the links to an intermediate page that is blocked from search engines with a robots.txt file do they mean using a website such as... http://hiderefer.com/ and http://anonym.to/ or something else?
Many a times people buy or sell links from high PR pages to pass on some pagerank juice to their site. Google doesn't allow this as that is against their guidelines. But Google understands that not all paid links do this for passing PR. So, it asks site owners either to redirect the link through an intermediate page which is blocked for search engine bots using robots.txt or make it a no-follow link. Hence, there is a message of redirection.