I am working on a native Cocoa based editor, with the goal of having a reasonably high quality editor for iOS devices. I’m starting with a Cocoa-based desktop editor, will then port it to iPad, and then to iPhone. It will never have all the features of JOSM, and possibly not even Potlatch, but it will be a fast, friendly, easy to use, mobile editor whenever your primary device is an iPhone/iPad and you’d like to do some OSM editing.

If you wonder why we need yet another editor, RichardF (primary author of Potlatch) has a nice overview of the need for new and better editors in his blog (http://www.systemed.net/blog/index.php?post=24).