I'm typing this now with my left hand on my main keyboard and my right hand on my laptop keyboard, which is about two feet away and at an angle. It's surprising how natural it feels to type this way.

I don't have any particular RSI issues, so I probably won't make a habit of it, but it's interesting how my brain doesn't seem to care how far apart my hands are. I'm not even consciously aware of which hand I'm using at any moment.