Although Cutts has said that using nofollow for internal links is a no no, I have not seen a discussion anywhere regarding the use of nofollow on reductive navigation links.
We have our link structure setup pretty solid, however when somebody gets to a final landing page we provide the customer with reductive navigation on that page to further narrow the product selection. However, we do not want Google to follow these reductive links as the resulting product pages have duplicate product subsets of the previous page. I fear that the reductive navigation pages could take away from the main landing page that is our focus.
Thoughts on using nofollow or another technique to stop Google from giving any weight to the narrowed reductive pages.
Just to note: Target currently uses nofollow on their reductive navigation, wherein Amazon does not.