Hello WPMU Dev,
iThemes have a premium webinar on how to use CustomPress scheduled on the following date:
PluginFocus - CustomPress
Monday, Feb 4, 2013 1:00 PM - 2:00 PM CST
As I am a paid member of Webdesign.com, their subsidiary that runs these courses, I can book a place.
Normal price for those that are not members is $27.
Do not know what your business relationship is with iThemes but it does appear to be in WPMU Dev's interest to promote this webinar.
Apologies if you already know about this, feel free to mention Yusef.