Poser 7 now allows you to organize libraries into content collections (pg 52 in the ref manual) where you can pull things from various library categories and runtimes.

If you're looking for something to automatically sort every bit of content you install into some sort of categorical system, there isn't anything out there. Content creators have their internal system to install content (usually under their name rather than under a generic product category). Maintaining a well-organized runtime is a manual effort that you have to perform after you install products.

You can link to your old Poser runtime if you don't want to reinstall all your old content into Poser 7.

My visual indexes of Poser content are at http://www.sharecg.com/pf/rgagnon