Photoshop CS2 breaks through the 2 GB RAM barrier. According to Adobe's press documentation, "Photoshop CS2 can address approximately 3.5 GB of RAM on a Power Macintosh G5 running Mac OS X, or on a Windows XP 64-bit Edition system running an Intel Xeon processor with EM64T, or an AMD Athlon 64 or Opteron processor."
A new "Merge to HDR" command lets you combine multiple exposures into 32-bit high dynamic range (HDR) images.
Shadow/Highlight can now be used in any 8 or 16-bit RGB, LAB or CMYK image.
More filters have been upgraded to 16-bit compatibility, including Liquify and Lens Blur.
I'll continue to update this page with the best Photoshop CS2 and Creative Suite 2 information I can find over the next few days so keep checking back.

Adobe Press Release: 
Photoshop CS2 software brings a new level of power, precision and control to the digital photography experience and to the overall creative process.

"Photoshop CS2 pushes the envelope with powerful features and simplified workflows that provide photographers and creative professionals the freedom to deliver stunning images," said Bryan Lamkin, senior vice president of Digital Imaging and Digital Video Products at Adobe. "In light of the four million digital SLRs expected to ship this year, more photographers than ever will be making Photoshop CS2 their digital darkroom of choice."

Advanced Tools for Digital Photographers, Graphics and Video Professionals
Photoshop CS2 integrates a new set of intuitive tools, including an enhanced Spot Healing Brush, for handling common photographic problems such as blemishes, red-eye, noise, blurring and lens distortion. Smart Objects allow users to scale and transform images and vector illustrations without losing image quality — as well as create linked duplicates of embedded graphics — so that a single edit updates across multiple iterations.

Responding to requests from film, broadcast and video professionals, Photoshop CS2 now allows non-destructive editing and the creation and editing of 32-Bit High Dynamic Range (HDR) images, ideal for 3D rendering and advanced compositing. FireWire Previews can also be viewed on a television monitor through a new direct export feature.

Photoshop CS2 users will test the limits of creativity with new tools like Vanishing Point and Image Warping. Vanishing Point cuts tedious graphic and photo retouching tasks by allowing users to clone, paint and transform image objects while retaining visual perspective. Reinventing workflows such as product packaging development, Image Warping makes it easy to fold, stretch, pull, twist and wrap an image into shape by selecting an on-demand preset or dragging custom control points.
Advanced photo editor (serial number 1045-1412-5685-1654-6343-1431)