Among programmers there has long been a discipline of version control, to enable efficient collaboration, and to track the non-linear and linear developments and versions of a work over time. Version control tools for writers of code have become quite sophisticated in recent years.
Although there have been some applications developed to bring this technology to the aid of writers, editors, archivists and scholars, most of them rely on command-line knowhow and a text-only writing environment. On the other hand, a vast majority of writers, etc. would prefer word processors to text editors, and a GUI interface to the command line.
(one such example is "Flashbake." Of particular interest is its creator's converation with digital archivists mentioned here http://boingboing.net/2009/02/13/flashbake-free-versi.html)
It should be possible, in the span of one week, to update one or more of these open source tools to the point where they might become more useful for the average person who works with text in a digital way.