John Welch at the TTABlog is a great resource for keeping up with the current state of affairs in trademark law. He recently pointed to a case where a trademark registration was invalidated because the Board found that the registrant had committed a fraud on the office. The fraud was committed when the registrant alleged in a statement of use that all the goods and services identified in a class were in use, when in fact only some of those goods/services were being used.
TTABlog now provides a very well-written article on the current state of affairs in fraud matters at the PTO. The article is by Carrie Webb Olson and is a must-read for all trademark owners and their attorneys.