Seth Dillingham: My First Core Image Filter (for Acorn).
It's a quick little Core Image filter that converts white to to alpha, and the grays to opaque. He asked me last week if such a thing was possible in Acorn and I got to say "Well, not quite- but here's a little ci kernel to get you started".
I was pretty intimidated with Core Image when I first started using it, but I'm glad I got over that. It's a pretty powerful framework and it's ridiculously easy to get things going in it. If you're a developer and you haven't checked it out yet, you really should.