I think this issues is raised with the co-auther note, but it's slightly ambigious what's meant. Therefor I'll just restate that an option to collaborate and work seamless across workstations in the same InDesign document would be very helpful. Something similar to the Office-package in this regard would be amazing, where you can see what and where the other collaborators are editing and in what sections. It's a hassle to have multiple copies and remember to copy every edit into a masterfile in the end.