A new update for Premiere 4.2 has been released and will install automatically if you computer is connected to the internet.  An update for Adobe Media Encoder is also available.

Mainly the update fixes a few bugs. However the most significant changes are that it now supports the new Panasonic AVC-Intra (which is nothing to do with AVCHD) and there have been changes which mean that Black Magic and AJA cards will work better.

Here is the full list of what's new:

* Panasonic P2 AVC-Intra material is now supported; new sequence presets are also included for editing this format.
* Final Cut Pro Project Converter is now compatible with Final Cut Pro version 7
* Final Cut Pro Project Converter now maintains timecodes from the originally captured sources from Final Cut Pro
* Playback no longer stops when connecting/disconnecting a USB keyboard or mouse
* Performance is no longer diminished in mixed format sequences during playback, scrubbing, and exporting
* Fixed a field output issue when rendering a 720p 60/50 source in an interlaced SD sequence
* Third-party support

Known issues

* Use of Project Manager is not recommended for AVC-I since clip spanning is lost during project collect and copy
* Clip duration in media browser does not match duration of clip once it is imported
* AVC-I clips are redbar in native sequences

DO NOT INSTALL THE UPDATE IF USING A MATROX CARD LIKE THE RT.X2.  There are known issues with the Matrox cards and Matrox are working on new drivers for use with 4.2.