A. TONS.

I’m sure you already know about Camera Raw 7, and you’ve probably seen bits about selective blurring & adaptive wide-angle lens correction–but what about Skin-Aware Masking, smarter Auto Curves, 64-bit Bridge, an improved Print dialog, and more?  Check out this comprehensive overview from photographer & Photoshop PM Bryan O’Neil Hughes.

On a related note, photographer & author Martin Evening has posted a great in-depth piece on DP Review covering extreme contrast edits in Lightroom 4 and ACR 7.  I love being able to get more of the benefits of HDR from a single frame, and without introducing garish haloes.