My exact thoughts (and no doubt many of you). Jobs will present Leopard himself for sure yet they need it in time for NAB one has to think and he won't do it there, it's not his MO. That seems to point to a 'Steve Special' prior to NAB.
Considering the list of bugs shown for Leopard at AI today, I don't think we'll see any traces of the new OS until June...but yeah, I still want my 12" MBP...