i don't understand why a p2p proggie hasn't used a system similar to what dynamic ip people use to get their own web addresses (like
http://www.dyndns.org). every username/password connects to a central server that records their current IP address. When you check someones hotlist, you check that server which spits back the ip address currently associated with that username and then you contact them. It's what audiognome needed ages ago to make their pnp thingie work (and he never implemented i don't think).
i pointed out that there might be a legal problem with this idea some time ago, and someone responded that if this kind of lookup from a centralized server was illegal, then the backbone of the web is illegal for associating a warez url with a numerical ip address. I think that person was correct and this kind of lookup is pretty much on the safe side legally.
If there even was any question, the safest way to do it legally would be to get a 3rd party company to provide the service of connecting username to ip addy. maybe dyndns.org for example; since they are essentially doing this service already. that would make any legal arguement the media conglomerates come up with all the more difficult.