Glad to see that contenteditable-type editors are becoming more viable. Looks like Copybar uses Redactor, but I'm hoping bergie's http://hallojs.org/ gets a lot more traction since it's the only one that's MIT licensed.
The good thing about Hallo is, besides licensing and easy plugin development, the fact that it uses plain, unstyled contentEditables, so the stuff you're editing looks exactly like it will look on the real page.
I integrated Redactor as another editor option in Create.js a while back, but it looks a bit strange because it changes the styling of the currently active content area. Other than that it is very simple and clean!