Coming from an little more experienced dev (not that experienced with OSS) point too, I think some little exercises on the dw codebase would be awesome, just as a little more structured way to poke around and get comfy. Also including as much of the normal workflow including source control would be awesome.

I just ran through getting up and running over on OTW and while the generic 'make a blog on rails' intro exercise is probably great at getting newbie devs' feet wet, I know all that about rails already. I want something that lets me poke in the existing codebase without breaking something.

(For the record I'm a Java dev, have hardly touched Perl or Ruby before but slowly working over into the Ruby/Rails world, so I have a leg up on that side.)