Blender 2.63a Release Notes
Bug fix update
Over 100 bugs fixed since 2.63 release:
- Fixed errors found in BMesh integration.
- Fixes for various crashes in bmesh, rendering and compositing.
- Fixed various drawing bugs with sculpt and paint modes.
- Animation motion path improvements r46158
- Improved OpenCollada support.
- Sequencer and movie clip fixes.
For a full list see: 
The original release log: