Apple support site updated for Leopard
Now that the cat is out of the bag (man, I have been holding that one in for too long), Apple's support pages have been updated with new and revised articles covering all things Leopardian. There's a support feature page on 10.5, and you can also search the site for all articles with the "kmosx5" tag.
As noted earlier, the developer site is also reveling in Leopard goodness, so ADC members (free to join!) can review loads of system documentation at leisure.