Adobe has just posted Photoshop CS4 and Bridge CS4 Help on the web. They still have some work to do and bugs to fix, but I thought you might like to take an early peek.
Note that links to video tutorials and to some other Help documents are not functional yet, and commenting isn’t turned on. This will be fixed when CS4 ships. Search works now, and the quality of the results should improve as these new pages are crawled by Google.
TIP: Download the PDF from the upper-right corner of any Help page on the web. The PDF is great for when you’re offline or want to print a version of Help.
And finally, here is more info about the new Adobe Community Help system, in general.