Excellent Nicola, that opens up a bunch of possibilities for scripting/baking rbArrays within Maya!
For a moment I didn't think it was working because on frame 1 the positions and rotations were still reported as 0. I noticed a simulation step needs to be run before positions and rotations are populated. Also, when the scene is rewinded the values don't change (they remain at their last value). I guess I'll just have to assume that if we are on the first frame, to use initialPosition and initialRotation... or... how difficult would it be to have them populated at the first frame as well?
Thanks Nicola, much appreciated.
Edit: BTW, there appears to be a 4K maximum for rigid bodies? (on my Windows 32-bit with Maya 2008 anyhow; and it doesn't appear to be a RAM / PC resources issue)... I can create up to around 4000 rigid bodies and everything is fine, but if I hit 4096, then Maya crashes. For example, if I create a sphere array of 16x16x16, then Maya crashes. Perhaps, if there is an internal limit, it should be caught.