I'm just hoping that it's a late April Fool's joke, but according to this article over on Engadget, Leopard won't be released until October.
They say it's because they had to steal resources from the OS X team to work on iPhone.
Mind you, having looked at Leopard recently, I'm not sure I really care. None of the announced features were of any interest to me.
Hopefully, by October, that will have changed.