This is the long awaited Panels 2.0 beta 1.
At this point the API is frozen and the feature set is basically frozen. Notes:
1) When installing this beta, *remove* any prior install you have from the file system, as 2 files have been removed. Their presence will cause conflicts that will cause your system to crash. if you get into this position, remove your panels directory and re-install from the tarball.
2) If you're taking advantage of exported panels and default panel pages and minis, you will need to re-export them.
3) There are a bunch of new modules included. You don't necessarily need to enable them all; in particular, unless you find you need it, don't bother enabling the legacy nodes module.
4) Any 'panel style' modules such as tabbed panels or the panels carousel will need to be updated for some theming changes that were recently made. Therefore, please check these modules before you update, or be prepared for those things to not work until they are updated.
Important safety tip: Panels 2 beta ships with two new modules dealing with Views: panels_views and panels_views_legacy.