There are tons of speaker docks on the market today that will work with the iPad and the iPhone. There aren't that many available that will work with the iPad though. If you want, a dock that will charge your iPad while you listen to music or watch video iLuv has a new offering for you. The new iMM747 speaker dock will support any dockable Apple device.
One of the cooler features of the dock is that you don't have to mess with those little cradles that you have to exchange to support different devices on some docks. The iMM747 has an adjustable back that will work with any dockable iPod, the iPhone, and the iPad without those trays. The speaker dock is larger and wider than many we see thanks to its ability to work with the iPad. The dock measures 14.3" W x 5" H x 3.7" D and weighs 2-pounds.
The dock needs quite a bit of power at 15W for operation. It has a mini USB port that allows you to synchronize the docked device without having to pick it up. A 3.5mm input allows non-dockable players to be used with the dock, and the power adapter needed is included. The iMM747 will ship soon for $149.99 and is one of the first iPad docks around.