MacRumors.com

An unverified anonymous source claims that Apple stores are receiving materials for a new window display that's labeled "do not open until Tuesday, May 9th." The source also claims that Apple has directed its stores to push iBook sales this weekend, presumably to clear out inventory.

Recent rumors have pointed to the Macbook being released in May, but no specific date had been given.

Update: (Moved to Page 1) In addition to receiving further confirmation of more Apple Stores receiving materials for a Tuesday product release, http://www.apple.com/ipod/ looks like it is spilling the beans with a reference to the as-yet unreleased Macbook. In case the site is corrected, a screenshot is mirrored here (emphasis added in image).

Update 3: Other reports claim the MacBooks will come in Black and White configurations.