In Furl when you visit any individual's archive page you will see that the sites are not directly referenced to.

They are redirected from a jsp script using the dreaded 302 redirect. It has the effect of potentially replacing your page in the search engine with a furl page.

Sometimes, an HTTP status 302 redirect or an HTML META refresh causes Google to replace the redirect's destination URL with the redirect URL. The word "hijack" is commonly used to describe this problem, but redirects and refreshes are often implemented for click counting, and in some cases lead to a webmaster "hijacking" his or her own URLs.

This is definitely not acceptable.