Well we have some strong rumors that WWDC will see Leopard being released.
What will probably happen is Apple will unveil new MBPs/MBs around May and start a count down for Leopard (you will get a free upgrade if you purchase after the next upgrade's release date has been announced).
It will probably be Apple's excuse to scrimp on the displays on the laptops for one more revision since the Macs released then still do not have Leopard preloaded.
That's my prediction, you heard it here first.