That is more in depth than the posted article. Doesn't mention three things I would think would be needed though..

Live updating of document section numbers/names and references back to them. Lots of named clauses in legal docs.

Workflow and electronic signatures.

Support for rendering as word docs or PDF files.

Proprietary tools that do those sorts of things are currently penetrating the market, yet slowly. I've been called to advise on a few projects under development, but have found the mindset behind them lacking for meaning or purpose beyond commercial activity, which is perfectly ok and useful – though what interests me most in this realm is version control coupled with open access and put to use by citizen groups for legislative proposals.

Check out Contract Express from Thomson Reuters (http://contractexpress.com) for the establishment's instantiation of something that approximates the features you describe.