Tim Stringer of TechnicallySimple.com has been hard at work creating a learning series called Learn OmniFocus:
Nothing’s up yet, but you can sign up for announcements there. I know he’s done a lot of work on Daylite, too, so he has experience creating learning series like this. I’m excited to see what he’s come up with.
Update (2013-12-22): Also, check out a new course Tim’s put together, which includes OmniFocus, starting up soon called: Holistic Productivity™: An Online Course Featuring OmniFocus™