If you don't mind not having direct capture, it's very easy to stream on Macs if you use a camera with FMLE alone or in tandem with CamTwist if you want some extra effects/options. I've already been doing this for a while, and it's like 500 steps less (and easier) than all that VLC stuff. If you feel like spending an arm, there is also
Wirecast which has a lot more features than FMLE.
On Windows the difficulty is about the same, except there are more options. XSplit is probably the most flexible piece of software on it right now. Before anyone asks, no it doesn't work in Wine. :(
As far as emulators and stuff on the desktop, the same FMLE + CamTwist combination works miracles. Perhaps I'll make a separate thread specifically to explain how to use them, as this thread is more about external devices.