I intend to extract the code from our project so we can share it, but haven't gotten around to it yet. It is a combination of Faye (for real-time updates), Rails for view rendering, and some clever Javascript that efficiently merges DOM changes. The last part is the key - it makes it efficient to update large parts of the screen without flickering, or needing to reattach JS event handlers.

The beauty is that it supports even the most complex reactive update use-cases. E.g. reactively updating sort order of a list for one user when another user renames an item in the list. The key benefit though is that you allows you to just write Rails code - there is no need to write Javascript for each new reactive view.