I’ve been observing some automated testing of our virtual worlds, and my machine keeps dinging. My teenager said, “Someone’s getting IMs.” Sort of.
Suppose you’re talking with folks in-world. Or suppose you’re talking to folks in the physical world and you have an open mic going into a virtual world. You want to know if someone else has arrived in-world. You can see them arrive, so you don’t have to monitor and decode some textual list of users as you would in a 2D collaboration tool, but you often also need an audio cue.
Our test suite includes people teleporting rapidly from one place to another. Our sound for someone arriving virtually is about the same as the arrival of an IM on a phone. You don’t want something as obtrusive as a ringing phone that must be answered. iChat has a subtle little puff of air when someone’s status changes, which is so much nicer than AIM’s horrible ad-laden advertising. (My wife works in a home office upstairs and my home office is downstairs. But we can’t intercom by IM because she’s on Windows and AIM is just too horrible. I wish Apple could make a Windows version of iChat to join their ports of iTunes and Safari.)
You might want to search for Pidgin, a cross-platform multiprotocol IM client.