There is no way that Nokia could handle this situation without upsetting no one.
If they not announced the N900 it would be dead just before launch, cause it is a open source phone.

The only thing I would recommened is, that they pushed the date back when taking pre-orders.
I think it's clear, that there will be some feedback when Nokia gives away 300 N900 for testing and start making programs.

I hope this device will not fail and all crybabies will crush the phone they bought instead of the N900 because they were just fed up waiting.