The error 'command not found' means that the command is not found in the $PATH environment variable.
If you installed blender as described in the Wiki Installing Blender on Mac. The executable blender is located in /Applications/Blender/blender.app/Contents/MacOS
You could simply open your terminal and enter
cd /Applications/Blender/blender.app/Contents/MacOS
./blender
ndof: 3Dx driver not found
found bundled python: /Applications/Blender/blender.app/Contents/MacOS/2.68/python
This answer is incomplete since I couldn't manage to add the directory /Applications/Blender/blender.app/Contents/MacOS to the PATH variable in order to launch blender from everywhere.
Unfortunatly the Docs don't cover this topic.