There has been a lot said recently about the effectivness of the rel="nofollow" attribute with regards to internal PR.

Many SEO professionals believe that the rel="nofollow" is the golden nugget for funneling PR from non themed pages (contact, terms, clients, login pages etc.) to their most important on-topic pages. The Efffect? The PR that was allocated to the non-themed pages will then be passed on to the on-topic pages, thus helping rankings of the latter.

I can see how this would work short term, but I can also see how in the long term the SE's will treat this as a black hat technique as the site owner is effectively manipulating PR.

An alternative to 'nofollow' would be to use a robots.txt file and exclude spiders from indexing the non-themed pages - the big question is though would this technique accomplish the same goal and funnel PR from the non-themed to the on-topic pages?

IMO the robots.txt method will accomplish PR funnelling and is the truly ethical way to go, you may disagree though. Let's discuss!

Thanks for reading! Lee