Something for trademark lawyers to do when its slow: search Wikipedia to see what it says about your brands. One reason has to do with preventing genericide (I suspect that the lawyers for THERMOS and PING PONG have been in conact with the folk at Wiki.
There’s also the corporate image thing. Pick any controversial corporation and check out the listing.
Discussions about the Wiki editing process here and here.
UPDATE: Wikipedia will require registrations to post – discussion here.