The Electronic Frontier Foundation has the best collection of links about the legalities concerning filesharing in the US
for example, here is a link to the recent (Sept 2004) advice to the makers of filesharing programs
http://www.eff.org/IP/P2P/p2p_copyright_wp.php

For Canadians, http://www.canfli.org/modules.php?op...q=yes&id_cat=2 is the best guide I've found to filesharing issues

LimeWire itself has this page http://www.limewire.com/english/content/ftc.shtml

Short answer? It's legal as long as you don't use it for anything illegal, and lobbies are daily trying to get control of filesharing.