All-Done is a third-party iPhone app that brings Ta-Da List to your iPhone. You can use it to sync your lists with tadalist.com, add lists and items, and move/copy items from one list to another.
Developer Andy Steinmann emailed us about the app:
I have been a fan of TaDa List for quite awhile. However, I have found that the iPhone web app, while very functional, was still a web app. Wanting to further my iOS development skills, I undertook the task of creating a native iPhone/iPad application that interfaces with Ta-da Lists. After several months and a fair amount of Fiddler and HTTP Client usage, it's ready.