From the release announcement:
The Blender Foundation and online developer community is proud to present Blender 2.67. New in this release is the Freestyle render engine for non-photorealistic rendering, which can generate 2D line drawings in various styles.
The paint and sculpt system is now much more consistent across different paint modes and has gained various new features. Motion tracking was made faster, and Cycles now has initial support for subsurface scattering.
The node system now support more flexible group editing. For developers of external render engine addons it is now possible to support node based materials.
For 3D printing an addon was added to analyze and export the meshes.