The Camera Raw 5.3 and Lightroom 2.3 Release Candidates are now available on Adobe Labs.  Please note that these updates are Release Candidates and not final releases of the software.  As Adobe puts it:

The ‘release candidate’ label indicates that this update is well tested but would benefit from additional community testing before it is distributed automatically to all of our customers.

Camera Raw 5.3 Release Notes:

Newly supported camera models include:

• Nikon D3X
• Olympus E-30

This release is not currently compatible with After Effects. This will be addressed before the final release
This release addresses possible artifacts that could appear in Canon EOS 5D Mk II sRAW files.

Lightroom 2.3 Release Notes:

The goal of this release is to address several bugs and provide additional camera raw support. A list of issues fixed in this release is included below:

Bugs – Fixed

• In the Windows 64-bit version of Lightroom an sFTP upload process could cause Lightroom to crash.
• Slideshows could return to the first image randomly during playback.
• A memory leak could cause Lightroom to crash while attempting to process files with local adjustments.
• Canon EOS 5D Mk II sRAW files could process with artifacts in Lightroom 2.2.
• Lightroom 2.2 could cause disc burning to fail for Windows customers.

Camera Support

Newly supported camera models include:

• Nikon D3X
• Olympus E-30

Additional information and download via the links at the top.