Hi,
Now that it has been released, I thought I would say that the TG2 Tech Preview on Mac OS X 10.5 Leopard appears to work as expected. I don't yet have my shipping version of OS X 10.5, but it runs fine on the last developer release. As always, if you find anything untoward happening please let us know, and do mention if you are using OS X 10.5.
Regards,
Jo