Matthew E May has How Intelligent Constraints Drive Creativity at HBR blogs. It's a topic I've come across before - particularly because of the constraint in the title.
An intelligent obstacle or constraint is one laden with creative tension, whether stated in the form of a well-defined problem ("How might we simultaneously decrease both inventory and backorders?") or a challenging goal (NASA's 1990s mission to land a rover on Mars in half the time and a tenth the budget of the previous mission). An intelligent constraint informs creative action by outlining the "sandbox" within which people can play and guides that action not just by pointing out what to pursue but perhaps more importantly what to ignore.
This time the article was forwarded by a friend with whom I'd just been discussing the ideas behind Theory of Constraints. The focus of TOC is productivity and getting results for the organization, not creativity directly. However, think there are parallels between the worlds. If you know and acknowledge where your constraints are you then get to expend your energy on doing as much as you can in light of the constraint. The TOC mindset is that as long as the constraint "makes sense" and cannot be removed easily that the rest of the work has to be focused on dealing with the fact of the constraint. The opposite is the situation where the constraint is hidden or unknown, so improvement efforts go about doing all sorts of things and do not necessarily provide the greatest benefit to improving flow - flow of results.