You mean the regular dock? I don't see why not. If you are talking about the keyboard dock, I would guess not with the current OS, but OS4 might make the iPhone compatible with it. I give it a fifty-fifty chance.
yes I believe that the iPad dock will in fact work with the iPhone, it will just look a bit awkward. Both the iPad and iPhone have 30 - pin dock connectors so all iPod connectors will work with it. Plus the iPad is a bit thicker then the iPhone, so it should fit.
...but the older 30 pin iPod adapters won't charge the iPhone, the same could happen here. The real answer it seems is nobody knows.
you seem to be under the impression that the iPhone software and the ipad software are the same which they are but at the same time there not. Parts of the software are enabled for iPhone and parts for the ipad. It's this that will stop things like the keyboard doc from being shared!
Thats because older accessories used firewire type charging that newer iPods and iPhones dont support. The iPad uses the same usb type charging that the iPhone and ALL iPods use so I see no reason why it wont work. I would actually be very surprised if the dock was not compatible with the iPhone.