I have just checked in a set of CSL source changes that will (I *hope*) make it possible to have a single file reduce.img built on a 64-bit machine that can then be loaded on either a 32 or a 64-bit system. This may be especially valuable on the Mac where one "fat" binary can run on either x86 or x86_64 (or ppc).
This may well have a side effect that existing images that you have and that ccontain an initial heap image will not load properly on the new version. Since this shoudl only have an effect on subversion users right now I think that they should all have the capacity to recompile their image files, and it only tales a few minutes!
In a while I *hope* to get things so that images built on 32-bit machines will reload on 64-bit ones too. That change will not (I hope) introduce incompatibility in that I have tried to plan ahead for it in this release.
If you try that loading of images across machine word-width please let me know if you find any glitches - there could still be some. And especially if you have a 64-bit image that fails to load nicely on a 32-bit machine please keep it so you can send it to me to help me debug the problem away.