I think your right, they probably did have some lawyers evaluate their MP3 search liabilities-- didn't realize it was on all Lycos properties though! (Shows you how often I venture off from Google heh).
Perhaps FAST isn't vunerable because anyone using a website to share an MP3 can be typically be tracked down and are probably violating the TOS of their ISP and a simple email can get rid of the violating MP3 site--
But an anonymous user on a P2P MP3 network, thats a bit tougher- then they have to go after the company offering the networking technology instead...
So mabye FAST is in the clear? We'll see what happens though if they get to be megapopular :).