The following issues were fixed in the Lightroom 4.1 release candidate 1 (March 29, 2012):
- Point Curve adjustments made in Lightroom 3 and before have been restored.
- Lightroom 4 did not properly open external applications when using the “Edit In” functionality.
- Addressed performance issues in Lightroom 4, particularly when loading GPS track logs, using a secondary monitor, and the controls within the Develop module.
- Ability to update DNG previews and metadata for more than 100 photos has been restored.
- This update allows for improved viewing of subfolders and stacks in folders with a large number of photos.
- It was possible that a layout of a saved book could be lost after quitting Lightroom 4.
Lightroom 4.1 is now available as Release Candidate 2 on Adobe Labs. 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. The final release of Lightroom 4.1 may have additional corrections or camera support.
via Lightroom 4.1 RC2 Now Available on Adobe Labs « Lightroom Journal.