Adobe has unveiled the help menu for Photoshop CS4 online... so if you want to check out some of the new features in-depth just head on over to their site – http://help.adobe.com/en_US/Photoshop/11.0/
You’ll find that the help system is still coming online fully... but there’s some great stuff to check out. Think of it as an appetizer until the real thing ships later this month.