Can I run rim brakes on a disc rim?
Some disc-brake specific wheels use rims that are not designed for rim brakes. To accomplish what you want you need a wheel with a a disc-brake hub and a rim-brake rim.

With that setup, assuming the fork widths are the same, you should be able to switch wheels between bikes without problems. The only drawback is the slight increase in rotating mass from having extra material in both the hub and the rim.

An example would be this wheel from Mavic available at Nasbar, but your LBS should be able to easily build up wheels for you if they don't have something specific in stock.

To use your dynamo I think you are forced to have custom built wheels, but it should still work fine.