Wired's Cult of Mac blog offers some uncharacteristic tidbits from a knowledgable friend who is only attributed as an "anonymous source".
This source claims that the Steve Jobs keynote that was delivered was not the actual keynote originally planned. As noted before, Steve Jobs prepares for weeks prior to the actual event.
Instead, the claim is that "some very, very cool stuff" was eliminated because of supply issues. The blame is laid on the Core Duo chips. When asked if the products were simply 12" and 17" MacBooks, the source claimed the unreleased products are "much cooler".
The reliability of this source is unknown so it should be taken with significant uncertainty. It is only posted on Page 1 due to prominence of the blog which will likely generate a significant amount of discussion.