Yes, I have been looking into that. What is really working for me is ORB, I am having a lot of luck streaming to the 3G iPad, even videos seem to work fine (not Media Center HD DVR recording though, not even close. I have been using 256 and 320kps mp3s, I have flacs, but haven't tested them yet. I wonder if the streaming software out there will probably use lossy compression for them (Orb, etc)...
The big issue is not to make the iPad play the things, but to make it play it VIA the interface I want (say, Leechtunes). Those things only work with the internal library.
I wonder if a local PC via airplay won't solve all the issues. But I'm not sure what works with airplay, perhaps not leechtunes, others.
That's why lately I'm leaning Android/back to CarPC.