Well, now you got me all fired up.
First off, I am very interested in getting deeper into C++. The only reason I feel more comfortable with Java right now is because that is currently what my college is using in some of the CS courses I am taking.
Second, I have an extremely simplistic console based chat between a server and client already ready to go. However, I would like to beef it up a tiny bit before I show put it out there. Right now I just have client and server talking to each other, but I would like for different clients to talk to each other through the server. I'll see what I can do. After I get all that set up, I'll probably make a GUI version. Hopefully I can get it done in a week, but we'll see. I have a pretty tight schedule right now.
Also, about the cross-platform stuff, I definitely agree. I mean I can even theoretically write games for my palm pilot now. That makes me happy.
I'll keep you updated.