Log Message:
Update to 2.66

Changes:
This release contains long awaited features like rigid
body physics simulation, dynamic topology sculpting and matcap
display.

Other new features include Cycles hair rendering, support for high
pixel density displays, much better handling of premultiplied and
straight alpha transparency, a vertex bevel tool, a mesh cache
modifier and a new SPH particle fluid dynamics solver.

In detail, see http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66