The 1.1 update brings the following functionality to the software: Improved RAW Image Quality, RAW fine tuning, Auto Noise Compensation, a New Color Meter, Enhanced Export Controls, Universal Binary Support, and other improvements.  You can view the detailed improvements at the Aperture update page.  Current owners of version 1.0 can immediately download 1.1 via OS X Software Update.

Apple has also added support for the Canon 30D and Nikon D200 Digital SLR cameras.

Apple has also lowered the retail price to $299 from $499 for new customers.  In a surprise move, Apple is offering a $200 Apple Online Store coupon for those customers who purchased Aperture at the prior $499 price.

View the Apple Press Release