This was going to happen eventually. Altec Lansing has produced the first fully iPhone-compatible speaker docking system. The descriptively named t612 features 60 Watts of power RMS (120 Watts Peak), and connects to your iPhone's dock port.
There are four speakers, enhanced bass, a wireless remote and, best of all, it's immune to that annoying GSM interference noise while the iPhone is docked and not in Airplane Mode.
All this convenience comes at a price -- $199.95US, to be exact. At the time of this posting, no shipping information was available.