There appear to be many changes in the upgrade from Photoshop Elements 2 to 3. The most obvious seems to be that it is now a suite of programs, rather than one big one, because Elements, which is now called the Elements Editor, now comes bundled with Elements Organizer. The latter, based on Photoshop Album, allows you to tag photos and move them into collections to make it easier to manage them. It probably won't be of too much use to me though, because the Elements Editor still has a built-in File Browser, which is the same as it was in Elements 2.
The Elements Editor has had a bunch of interface changes. The toolbox is now dockable. The palette tray has turned into a vertical palette bin. And each photo you open appears as a thumbnail in the photo bin at the bottom, which makes it easier to flip between photos. (not that I'll want to edit too many at one time) There is a new "Cookie Cutter" tool in the toolbox. Not that it couldn't be done before with selections but now, cutting out paw, stop sign, speech bubble, or heart-shaped pieces of pictures is a one-step process. There are no doubt many other new features but for now, I just played with the Elements Editor enough to make sure all the features I use in Elements 2 are still there. Well, indeed they are, and thank goodness Adobe didn't change any of the keyboard shortcuts.