As has become the norm for Lightroom releases, Adobe have announced a Release Candidate for Lightroom 4.3.
Release Candidates are beta tested versions with new camera and lens profile additions, as well as bug fixes. Putting them out before general release allows Adobe to check for other bugs on a broader range of machines
The major notes of interest in this release is full support for the Nikon D600, and for the new E-PL5 from Olympus (a baby version of thier wonderful O-MD E-M5).
Full details can be found on Lightroom Journal.