Is there any way of 'wrapping' a DOpus toolbar in a Windows Vista Sidebar gadget? Presumably a gadget could be designed with its own buttons/interface to call dopusrt, but using DOpus's native toolbars would obviously be convenient!
No way to do it at the moment.
There are some generic "make buttons which runs stuff" gadgets that you could hook up via dopusrt, as you suggest. For complex commands (i.e. more than one line) it might make sense to have the buttons call a User Command in Opus, which itself has the real command lines inside it.