You can download the Adobe Lightroom 2.0 BETA here.
Release notes here.
You can also check out the Adobe Photoshop Lightroom 2.0 Learning Center.
Enhancements that can be found in the Lightroom 2.0 beta include the following:
Localized corrections — Enhance specific areas of an image for unsurpassed nondestructive flexibility and control reminiscent of the traditional darkroom dodge and burn experience.
Improved organizational tools — Find the images you need quickly and easily.
Multiple monitor support — Add an additional monitor to efficiently manage photographic workflow and presentation.
Flexible print package functionality — Create custom layouts containing multiple sizes of a photograph on a single page.
64-bit support — Lightroom 2.0 now takes advantage of the latest hardware architectures with improved memory handling and performance.