i don't think they can block p2p activities - at least not on the long run. if they get isps to block the port: so what? the next client versions will be tunneling through port 80 then. take a look at groove http://www.groove.net (it's the new tool from the creator of lotus). it's usually using xml-transfers on some ports but auto-determins if these are blocked and goes down to http-tunneling if needed. same technology could surely be used also for gnutella. also take a look at the freenet project where you don't even know the files you are sharing on your machine.

there will always be a way. besides, most of us use files got from here to preview music or whatever. using gnutella doesn't mean you don't buy anything anymore, right?

about laws: in america they got through with the trial. in europe things look different. according to current laws it is not illegal to share copyrighted material for personal use. you are e.g. allowed to copy a tape to a friend. they are still on the way to position to this topic, but one cannot say this is necessarily an illegal activity.

and: if they are going to start trials, they need to start them against single users. it is unlikely that they will get providers to restrict services in general (and it wouldn't help). this also means they need a looooot of $s to investigate the different laws in different countries and then start trials with unknown outcome.

on the long-term they do not see a chance.