I'm not too sure, actually. Here are my two plans as of now...
Scenario 1:
Apple releases the MacTablet at MacWorld or WWDC 2009.
If this happens, I'm getting a MacTablet and a specced-up Nehalem Mac Pro to compliment it (and finally put a use to my twin 24" displays...).
Scenario 2: WWDC 2009 rolls around and there's no MacTablet by then. I'll wait for the Nehalem laptops to be released shortly after and get a specced-up 17" MacBook Pro and a 10+ bay JBOD drive array for my storage needs.
But I really want scenario 1.
Also, I approve of this thread. Should be a good one.
Or, scenario 3:
I get what's in my sig. Best of both worlds, but I'd really like a MacTablet.