Unless Apple has decided to use Yonah processors it would be hard for them to release the computers if there are no CPUs for them yet.
Apple could attempt to put pressure on Intel to give it the necessary chips early. So Apple is doing just that, and sources claim that it isn't flying as well as it had hoped. Any tale of cool, need or woe won't fly very far against the argument of "Dell sells 20 times what you do, why should we give you preferential treatment again?". Those same sources claim that this what Intel is saying.