While there are a number of high-end integration digital music servers on the market, including those from Escient, iMerge, and Audio Request, perhaps the most popular trend lately is the iPod interface.
I believe some of the newest receivers offer a iPod interface that allows you to control the iPod and brose your music directly through your television. So, not only can you run the must from the iPod into your system, but you can fully control it and start what you want playing from it just by using the remote that comes with your A/V receiver. Not entirely sure on that last part though.
Check Denon, Yamaha, and Pioneer for their latest offerrings.