Never heard of it till now (but just found their website orb.com through Google).
It appears to have to go through the internet from what their About screen says since you have to go to their website to find your server. I'd actually prefer a direct LAN connection.
That did give me an idea though, maybe I can just enable IIS and directory listing through my "intranet". I'm not sure if that will work, but it might.
THe Simplify Media app works great or this. ...it'll stream your music to people in it's userlist and iPhones. ..it's only problem is that you need wifi on the iPhone to use it because it streams.