Originally posted here by The Duck
I don't know about you, but after an attemptd DoS attack, I wouldn't be DCing with people while chatting, which is pretty mucht he only way to get someone's IP with IM's.
No, it isn't, several of the IM systems out there have IP lookups enabled. MSN Messenger REQUIRES UPnP enabled specifically for reporting this to the MSN server when doing voice chat and similar things. Even for regular IM use you can find it. IIRC there were several tools for ICQ, MSN, and YIM that allowed you to just punch in someone's account ID and then get their IP from the server.

That point aside, what you or I may do is irrelevant, it's important that people understand that it's a possible way for people to get your IP.