Apple just ordered 500 million 4GB flash chips from Samsung, this is on top of their long term contract with Samsung. This is far more than can be accounted for by the iphone or ipod demand (And are expected to be shipped by the end of this year.)

Intel announced Robson technology awhile ago, which ships in their "Santa Rosa" platform which is scheduled to ship in May - this month.

Apple has gone a bit longer than usual in releasing laptops... they are overdue for both MacBooks and MacBook pros.

On June 11th Steve Jobs will be giving the keynote at WWDC.

Last week Apple announced that they would be shipping laptops with LED based displays "later this year". Such a change will require a design change in the laptop- eg: a new formfactor. It might be like the aluminum books now, not really a new looking formfactor compared to the Titanium powerbook-- but thuroughly new internally.

Thus, I think the odds are very good that new laptops will be announced on June 11th and that the difference will be significant enough that its worth waiting a month before buying your mac.