I have some thoughts on the MacBook, and reading this thread has crystalised them to a degree.
This is an interim offering from Apple, it's a way of live beta testing a new product without having to force an entirely new design into production.
It will allow Apple to run it's transition to x86 in the public domain on a small user base.
It gives Steve something "wow" to show off and stops the bleating about the lack of new PowerBooks, plus it's 6 months earlier than the company were forecasting.
It is, as someone has already pointed out, a placeholder and I'm sure that a new line of laptops with a redesigned form factor will be forthcoming this year.
I won't invest in 1st gen hardware after a particularly crappy experience with the 17" PowerBook, but I will replace my existing 'Book when a 17" Intel machine is available and the software I need to run is in UB format.
This is a good move on Apple's part, but I think the iMac is the more impressive machine.