Outlook2003Bar changed to OutlookNavBar and is part of the new ThemedControls class.
ThemedControls contain another themed controls to complement Outlook interface (button, container, pageframe, etc).
Note that Buttons and Ribbon classes aren't finished yet.
So, be careful to use this two classes in a production environment!
If you are interested in help to develop the missing features in this two controls, please, contact me.
Check the ThemedControlsHelp.htm file in VCX folder for more information on how to use ThemedControls (except for Ribbon that isn't documented yet).