Unfortunately, No. I think Bearshare has this, though.

Also, it's more complicated than you might, at first, think... Remember, anytime you connect to an Ultrapeer, you automatically give them a list of all your shared files (so that they can filter what requests reach you). So, the RIAA/MPAA/etc just need to setup their own mesh of Ultrapeers and all the Leaf nodes will continue displaying all their files...

Ultimately, what may be required -- at least with the current state of the Gnutella protocol -- is to disable Browse Host and to run as an Ultrapeer (and maybe without peering with any other Ultrapeers?).