We're going to try and do a better job of keeping good github repositories of NYTimes open-source projects, but for a more focused selection, there's also http://beta620.nytimes.com/
Out of the box, you can do this in a very basic way. If you check out the tinymce demo version, you will see two buttons for accepting and rejecting changes which use ice's API (`acceptChange`, `rejectChange`) to modify the nodes.
We wanted the focus for ice to be on change tracking only so we intentionally left out track changes presentation/interaction details. I think there is a lot of potential for good UI/UX tools to be built for the track changes that ice produces and I would love to feature them in the project wiki.