Once I upgraded to Mac OSX 10.7.5, I noticed that I was unable to Right-Click my Magic Mouse. I found the solution HERE.

1. Click Finder > Go to Folder…
2. Go to the folder:  /System/Library/LoginPlugins/BezelServices.loginPlugin/Contents/PlugIns/
3. Copy the following files into the folder – Download Files HERE.
4. Reboot computer

Problem solved.