14 DAY TRIAL // Although it is currently a work in progress, the release candidate for Blender 2.67 brings to the table plenty of improvements and bug fixes.
The new build adds border for compositor viewer mode, which leads to faster previews because compositing is not done outside the defined area.
Cycles Rendering component now comes with support for subsurface scattering and minimum pixel size (Hair).
The developer added improvements to the Motion Tracker, making the camera and object motion solver more accurate and faster, on account of the Ceres library that is used for bundle adjustment step.
Additional enhancements include refactoring of The Paint System, as well as changes touching on tools and the interface for increased usability.
New add-ons are also present: Nodes Efficiency Tools (instruments that speed up working with nodes) and VRML2 Export (mesh only exporter).
As far as repairs are concerned, these are pretty numerous and some of them touch on 3D view, animation, armatures, audio, Collada, curves, game engine, mesh editing, objects, and the movie clip editor. You can find the full list on this page.