Apple's put up a gallery of the iPhone on their site, and two of the shots reveal the iPod dock-esque iPhone dock. It looks like the one we saw shown at MacWorld in January, but isn't the one we saw later in February.
That one had a slot for charging the Bluetooth headphone on the right, and was wider (obviously) than this one.
It sort of makes sense that the Bluetooth one wouldn't be the default dock, since not everyone will get a headset. This means that dock could come along with the Bluetooth headset as an accessory?