i can second johannes post regarding jacktrip.
in june we did a network concert between cologne and taipei, streaming 4 channels of audio at 16/441 in either direction + a skype video feed for projection in the theatre in taipei. even with a non fixed IP on our side (client) and using the general internet of our school (IT had prepared a fixed IP address for us, but it failed on the weekend we wanted to use it), it worked without a hiccup for the hour or so we used it. i was very impressed with jacktrip.
(sorry for resend hans, forgot to cc the list...)
Thirding JackTrip, if that's even necessary haha
I think,.. 4 years ago now? Something like that, we did a telematic concert between Stony Brook and UCSD and sent something crazy like 12 channels or something over JackTrip with relatively low latencies. Not low enough to do crazily rhythmically intricate stuff between the two sides, but low enough to feel like you're playing with the other side and not a just a video,.. (well I'd assume, I was on the tech side of things and didn't get to play). We also streamed video, it wasn't Skype, I can't remember exactly what we used (gimme a break, it was years ago). We did use fixed IPs and Internet 2, which prob helped the latency a bit. We also recorded all the channels into Ardour. It was a pretty cool experience, but long long days lol.
Derek