Just a small issue relating to publishing to the Playbook from Flash Builder 4.5. When launching the application onto the device you are greeted by a nice error telling you of an "ApplicationModeMismatchError."

The fix that worked for me was to go into your "Run Configurations" ( > Run > Run Configurations) and uncheck the "Clear application data on each launch" option - then run the app, then go back and recheck it.