this was posted on the unrelieable if fun macosrumors.com:
"Apple is known to have patented a "scroll wheel mouse" that uses a small iPod-like trackpad atop an otherwise familiar Apple mouse design; more recent recon suggests the new mouse will also come equipped to detect "right-clicks" when the mouse is pressed on its right side but that there will be no actual separate button.
This feature will only be enabled by default on PowerMacs with which it will ship; on consumer-oriented Macs, Apple's mouse drives will detect only standard single-button functionality from the mouse unless the user enables right-click detection in the Mouse preference panel.
In this way, Apple finally brings additional mouse functionality to market without breaking one of its core human-interface principles: no application should *require* or expect multiple mouse buttons by default."
Sounds like an interesting idea to me, embodying a compromise between the one and two button worlds. However, if it's not two buttons+scroll wheel (or some substitute), it doesn't sound worth it. The scroll wheel seems even more important than the second button, to me.