They provide hosting for the torrent files and also they are running trackers for the torrent files. The torrent network is backed by these trackers, this is a key difference between Google and them.
Either way, the pirate bay trial is a symptom of a bigger disease. I think this helps highlight that.
Torrent files in themselves are not illegal. They are simply pointers, its the trackers that are at fault. Trackers facilitate the ability to download illegal content, where torrents and a search engine don't in themselves, they just link to trackers.
On the same note... Go google :) I just find it funny.
So IMHO Trackers are not "at fault".