Aha! My router has checkboxes for TCP and UDP--both need to be checked and enabled. Which router do you use?

Might be a good idea to doublecheck the OSX firewall settings to make sure the System Preferences->Sharing->Firewall->New->Gnutella/LimeWire (6346) is active. Also confirm, please, that 6346 is the port used in the LimeWire->Preferences->Advanced->Port and Firewall sections

What a pain, eh! 3 differentsets of places to check (and risk screwing them up!)