I started by posting a link to the marching cubes algorithm but then I re-read the OP and realized it was the inverse of what you really wanted (it’s for skinning a voxel cloud instead of turning a skinned mesh into voxels, which was basically what the original post was asking for).
When I realized the link was useless I went to delete it - but too late, vbulletin doesn’t believe in deleting (or at least I don’t know how)
This, OTOH, might be the approach you want:
http://blog.wolfire.com/2009/11/Triangle-mesh-voxelization