Problem is that the Droid doesn't have a dock connector. You'd need to plug in the "dock" to the headphone jack unless it supported A2DP bluetooth. You'd be just as well off IMO with any stereo/powered speaker that had a line in.
Has anything else come out that can at least play music from the radio while charging my phone? If not I may as well just setup a dock next to my iHome that I had bought for my iPhone.