Rui CarmoWell, I don’t know if Acorn is what I’ve been waiting for (doesn’t seem to have color correction features), but anything by Gus Mueller deserves looking into for sure (via Ars Technica.
Update: Well, well. It doesn’t have a tone curve (my one true wanted feature on an image editing application), but it has a lot of color transformation primitives, HDR features, and (the cherry on top) a stackable filter architecture that is extendable in Python and lets you use filters and transforms as a simple visual pipeline - amazing, and a very, very nice new twist. I’m nearly sold on it.