It could be that 10.6 is the multi-touch version of OSX. In other words, it wouldn't have any new "core" features (such as quick look or time machine) but will instead be a reworked OS to work with multitouch. This would also explain why it would be intel and 64-bit only as only new Macs would be multi-touch capable.
This is what my money is on.
This is what my money is on.