Sony's SRS-GD50iP is not just a 2.1-channel USB speaker system — it's a 2.1-channel etc. with an integrated iPhone/iPod dock. Not to mention a big, honkin', bomb-the-bass subwoofer.
The USB connection servers a dual purpose. It lets your cradles iDevice charge and sync to iTunes, as well as acting as a general-purpose speaker system for your computer. The 60W total audio output should be able to handle METAL GEAR's biggest explosions, as well as whatever carefully-orchestrated white noise Trent Reznor dreams up in the next few years.
The SRS-GD50iP, which is compatible with a wide range of full- and Nano-sized iThingies, should be hitting the retail chute momentarily. Expect an MSRP in the US$150-199 range.