I think that Nikon are getting almost as canny in the marketing dept. as they are in the technology.
D90 + kit lens is a nice package, and today's announcements gives a very clear message.
Announcing any of the new lenses which many of us are hankering after - here I'm thinking mainly about fast AFS primes - would dilute this message, and can wait for another day (we all know that they are coming, so why spoil the launch of the D90).
I hope this doesn't sound disparaging towards potential D90 buyers - I'm sure that many of them are interested in lenses other than the kit zoom. I'm just a great believer in simple messages clearly delivered, so I think that Nikon's approach is sensible.