David told you that Adobe has finally released Photoshop Elements 4.0 for Mac. Elements 4.0 gives Mac users some new features they didn't have in Elements 3. Here's some more detail on what's new in Elements 4.0 for Mac:

The Magic Selection Brush tool.
To select an object with this tool, you just scribble or dab on the object. Elements does its best to select the object for you. You don't have to outline the object as in previous versions of the program.

The Magic Extractor.
Scribbling or dabbing on an object with the Magic Extractor both selects the object and extracts it from its background.

Skin tone adjustment
Click on an area of skin in a photo to set Elements to work automatically improving the tonal balance of all colors in the photo.

Straighten tool
Straighten and crop a crooked scan by simply drawing a line across the image.

WYSIWYG font menu
The font menu shows you what each font looks like so there's no more trial and error when selecting fonts.

Red eye removal
Elements 4.0 automatically removes red eye from your photos when you bring them into the program.

DNG export
Elements 4.0 includes Camera Raw version 3.3 for editing your raw digital photos. In Elements 4.0 you can export raw photos to the universal DNG format.

Adobe offers a chart comparing features in Elements 3 and 4 for Mac. To download the chart, click on Why should I upgrade? on the Elements 4.0 Mac product page. Dave mentioned that the Full Version of Elements 4.0 for Mac is $89.99. The upgrade price from a licensed version of Photoshop Elements, Photoshop LE, or Aodbe PhotoDeluxe is $69.99 at the Adobe Store. Oh, and by the way, Elements 4.0 is not Universal Binary for Intel Macs.