There might be an update in September with a new 'main' GPU and perhaps BluRay if we're very lucky.
But no changes on the integrated graphics GPU which also means no changes on the max RAM side as the Nvidia chipset only supports up to 8GB and we're there already.
And no change on the screen resolution either.
Intel Core i7 for mobiles were originally scheduled for September-December 2009 but were pushed back until 2010. So no i7 anytime soon.
And with
Intel's current quarrels with Nvidia about whether the next gen Nvidia chipset can support i7 or not it is possible that the Nehalem MacBooks will have to use a differnt GPU setup again.
Which might delay them quite a bit, perhaps well into 2010.
If you want Nehalem in 2009, buy a desktop.
And none from Apple (yet).