Not sure where to post this reply but my original question was non-answered then locked, and labeled not useful.
I just started using Blender on specifically on the very popular Macbook platform running Lion. Unfortunately, the most basic of commands (undo/redo) do not work using ctrl-z. The answer given was that undo is ctrl-z, even though I specifically stated that does not work.
Every Macbook user running Lion is going to hit this problem. The solution, it turns out is to disable mission control under system preferences for keyboard. I hope this helps others.