Through a Google summer of Code project, Francois Desjarlais, a student
in Quebec City, added the UTFGrid support to MapServer. One of the nice
addition he made is to add a way to request UTFGRid through a WMS
request. This allow for single tile grids that are dynamic.
In order to test this functionality, he created a UTFGridWMS Layer type
in OpenLayers. Pull request here with the example: