There is an interesting discussion on the usage of the WBS on the PMI Voices blog. I've used a WBS on many projects, but not in a traditional way. Here is what I commented:

The projects that I have been involved in have usually been small efforts, between 3-9 months. While a WBS was never a part of the consulting agreement with my customers, I have never the less created one for most of our engagements.

The primary intent was not to actually manage the scope via the WBS but to have a visual representation of the scope to engage our customers in discussions regarding the scope. The customers seemed to "dig it" when we showed them a graphical/hierarchical WBS that gave an overview over all the components that we are working on. They naturally understood the "org chart like" approach.

It was also a great tool to show progress. A green box meant that this particular work package was completed, yellow meant trouble and red meant behind schedule. The customers appreciated the simplicity.

So this wasn't necessarily a traditional usage of the WBS on my projects but it was a wonderful tool to help facilitate expectations management.

Has anyone else used the WBS in such an "out of the box" way?