Photoshop CS4 is now available, along with Camera Raw 5.0, a new generation of the Camera Raw pipeline. Version 5.0 doesn’t contain all the new camera updates from 4.6, but 5.1 will be released shortly to being them to par.
For Lightroom users, CS4 will automatically replace CS3 in the Edit in Photoshop menu item. To continue to use CS3 from there, you can select it as an external editor (note that an intermediate file is created with external editors).
For more info see Lightroom Journal