Short article on the value breakdown structure (VBS) at Jean-Yves Moine's 3D-WBS site
You can find it here on Jean-Yves' very interesting site.
A value breakdown structure is, along with critical path drag, drag cost, true cost, and some other metrics, a feature of the Total Project Control methodlogy. For those who are not familiar with the features and benefits of a VBS, I think this article explains the concept quite thoroughly.