That probably wouldn't be a good idea. It would screw up muscle memory and things like that, similar to the adaptive menus of Office 2000.
I don't know-- the XP and Vista adaptive start menus work well. They just have to reach a steady state, and then
the user can develop muscle memory.
The trouble with the Office adaptive menus was that they simply remembered the most recently used commands-- the Office adaptive menus never reached a steady state where you could start to develop muscle memory.