The latest and greatest version of Photoshop finally rolled on to shelves just a few days ago. I've been playing around with some of the new features in it and have this to say about them.
-First and foremost the application loads slightly faster than CS2 ever did, not by much but a few seconds saved on every start up is welcomed by me.
-The interface has been tweaked slightly, windows can now be collapsed into tiny icons, they can be grouped and collapsed/expanded together, docked on the sides. Multiple preset workspaces (which windows are open and where, and even shortcuts) can now be saved/loaded. This I find very nice, you can easily go from having the windows you need open for drawing/painting, to the workspace you need for creating a site layout or the workspace best for rendering. Pic 3 shows the default video workspace out.
-The curves function has been improved a little bit.
-Smart filters have been implemented. They are exactly the same idea as adjustment layers except with filters instead of adjustments (shown being used in pic 1).
-Few new tools to play around with, the quick selection tool as shown below is a very quick and easy tool to use to roughly select something from an image, took all of 2 seconds to get that rough selection in the 1st pic. The refine edge tool as shown basically improves your selection, it can smooth edges and make renders nice and slick looking (if used correctly), it works better on real images, not the greatest thing on Capcom art (note I'm not actually using the refine selection tool in that shot as everything but smoothing is to 0).
-There's a new Photomerge thing where you can take a few photo's of a location and combine them together to form 1 large panoramic shot. Apparently it has 'advanced alignment blending'.
-New better tool for changing colour photos to black and white (desaturation loses contrast and other details).
-Better cloning/healing options.
-You can do vanishing points in 3d now.
-And a few other things that I have yet to really play around with.
All in all CS3 is a dandy update to an already amazing image editing suite. I would recommend getting it if you can. There is also a CS3 extended version, it has some more 3d options, motion graphics and video editing capabilities, but really unless you need that stuff normal CS3 will do you fine.