Best described here http://www.gnutellaforums.com/downlo...tml#post348490
These are files with 'known' download hashes & known to have virus or spyware, etc.

I believe the objective (at least ideally) will eventually be to prevent these types of files being downloaded at all, however there needs to be a % downloaded to check the hash of the file. The LW Developers are still working on it I believe.