I was very glad to find this page earlier this week, after scratching my head while implementing an isometric renderer for a client. I had assumed it would be a simple back-to-front order, but this page and a few others pointed out that the partial ordering required to 1) use an intersection test to build disjoint sets of confused objects, 2) use a pairwise order test to determine inter-object dependencies, 3 ) use a topological sort to resolve the ultimate drawing order.

This method was implemented in some fantastic 1980s computer games, and the developer had named their technique "Filmation". Here's a discussion of that system, plus a demo of the rendering bug caused by not bothering to break dependency cycles as discussed in the main article:

http://bannalia.blogspot.co.uk/2008/02/filmation-math.html

(also I just found another with a load more details on the Filmation games: http://retrospec.sgn.net/users/nwalker/filmation/)