B&O were the first company to do this in fact, back in the 80s, and have been doing it ever since. I would recommend you go to a B&O dealer to get a grip of what it does, although it's difficult to get an idea of how well it works in a B&O store, and even more difficult to explain through BeoWorld...
As far as 'hard drive' storage of music goes, B&O offer a few solutions. The BeoSound 3200 is the most obvious, although this is a very simplified system (for the better or worse depending on how you look at it). IMO, the most up-to-date way of doing it is with the BeoPort, which will connect to BeoPort software on a PC or iTunes on a Mac and allow you to distribute the music from your computer around your B&O multi-room system...