If you're itching to get your hands on this source code, you'll have to wait a few more hours while I wrap up a first draft of this new tutorial.
By the way, did you know that Tim Boudreau's Paint App Tutorial has been completely updated? Check it out. That app rocks—it's the closest thing to a Quick Start Guide for NetBeans Platform development as you're going to find.
Postscript: Check out this really cool tip (that I heard about last night at a party) in Martin Adamek's blog!