In the early nineties, On Technologies released a wonderful product, called Instant Update, which allowed multiple workers to view and edit a shared rich text document. Many authors could edit the document at once, changes to separate paragraphs were resolved automatically, and a simple dialog box let you choose how to resolve each conflict. Each paragraph was marked as to who last modified it when.
Unlike Microsoft Word, which now does some of this (but didn’t then), publishing your changes was as simple as pressing the “Update” button.
At Apple Cambridge, we used this to collaborate on design discussions within the office, and between Cambridge and California. (Larry Tesler was a frequent contributor from there.)
I’ve missed this tool for a long time. Lately, at Laszlo we’ve been using a wiki for technical and planning discussions. This seems to be the fad in engineering organizations, and justly so.
A wiki is just Instant Update without the wysiwyg interface, without the line-by-line conflict resolution, but implemented as a web application, so that it can be universally deployed.