Over at Pivotal they recently blogged about the typical wrist problems that plague developers. In one of the comments someone mentioned a solution a number of us have come across at some point, mousing left-handed. When I have wrist problems (and a number of colleagues have confirmed the same) it tends to be in the right wrist. My problems come from mousing too much, rather than typing. This is aggravated by the fact that the numpad on full-sized keyboards is typically on the right side since people 10-key with their dominant hand. This setup pushed the mouse hand even further out of ergonomic alignment, though.
On the other hand, the layout is perfect for mousing left handed: the mouse starts closer to the optimal hand position and you can enter numbers while mousing. It does take some serious adjustment if you have been using computers for your whole life, but that is actually an added bonus – it gives you additional incentive to work on your mouseless operation while you are stuck in the awkward adjustment period. If you stick with it for a while, you will remap your brain enough, though. And, just like learning to brush your teeth with either hand, the flexibility is useful, for now you can flip-flop as needed to even out the wrist strain.
The new Apple flat (wired version) is perfect for that, since it returns to the tradition of a USB port on either side of the keyboard, for plugging in the mouse and/or another device.