Leopard will be preannounced in the next few months. I have only one wish for it. No, not XP virtualization -- we have Parallels and that will suffice for me.
I want a remote access capability that's at least as good as Microsoft's ancient remote desktop protocol. This is a capability Windows has had built-in (XP Pro) for eons. True, Apple has something called 'Apple Remote Desktop', but I've never seen it in action. I don't have a trusted source to tell me if it really works for remote control. Not to mention that it costs more than a new version of OS X.
I believe Jobs has decided not to do this (ever?), and I expect to be disappointed. Other than that, there's not much in Leopard I'm likely to care about. (Vista? Surely you jest.)