I don’t suppose someone knows of any prior art, do they?

CNET News.com –

[Quote] Patent creates IM wrinkle: “America Online quietly secures a patent that could shake up the competitive landscape for instant messaging software.” [Quote]

If AOL ever does decide to go after other IM networks, well – that would not be a good thing.

Would a Unix chat system, or (IRC even?) count as prior art?