I know for a fact that I did read it would theoretically be possible, although it was in the early days of Leopard, didn't read that it was official or tested, and after that would assume if anything it would only work if installed from a retail disk as the system restore disks would be specifically Intel related.
While the Leopard disk can be installed on either, is that something that is ever possible? After software/drivers I suppose it would only then be possible if you could change the partition table from GUID to Apple Partition, which as far as I know can only be done while formatting.