[There was a bunch of very cool Tri/Quadcopter stuff on the RCG blogs today. Here's a sampling:]
Above: A very cool custom tricopter with a Trex body so you can tell which direction is forward. Check out the post for details on the pro quality pan-tilt camera mount.
And check this next one out. Did you know that you can make a Mikrocopter amphibious? This video is mindblowing. It starts underwater, but keep watching:
Finally, a "best of" video of Mikrocopters as camera platforms. How many Hollywood movies or TV shows have you seen recently that used quads rather than cranes?
Both of those quad videos are from this post, which is great introduction to Mikrocopters. Worth reading the whole thing.
While i didn't design the motors, I have taking them apart to have a look. The Brushless motor is built into the pressure housing. The coils remain on the dry side around a recess in the housing, and the rotor with magnets slides into the recess and is secured with a screw. This way, there is no breach in the pressure housing for a shaft. This design has been around for a while and works very well. However, it's most likely to complicated for a DIY'er, as it means you are basically building and designing your own brushless motor, and have to have some major milling equipment to fabricate the housing with recess for the motor's rotor.
@Bill - Been working on a plan to remote my B-in-law's underwater fish cam... So your brushless motors are inside a sealed compartment and not actually in the water?