DFMXpress was a new tool that was introduced in SolidWorks 2009.  In SolidWorks 2010 there have been 3 minor updates to the program that should make this even more valuable to users who are designing in a manufacturing environment.

DFMXpress is a product delivered by Geometric.  This tool is the light version of DFMPro which looks for and finds areas of your design that are difficult, expensive, or impossible to manufacture.

Sheet Metal Validation

DFMXpress in SolidWorks 2010 now gives you the ability to validate sheet metal parts.  As you can see below you can check your sheet metal part against such rules as hole dia. to thickness ratio, part edge distance to thickness ratio on a simple hole and also a countersink, spacing to thickness ratio on a simple hole and also a countersink.

Managing Standard Hole Sizes

You can now specify the standard hole sizes used by DFMXpress to validate parts.  You can access this by clicking Settings > Standard Hole Sizes > Edit.

Zoom to Selection

You can also quickly view a failed instance by RMB clicking the failure out of the list and selecting Zoom to Selection.

DFMXpress is a tool that is probably not used all that much (I may be wrong and I kind of hope I am).  However, with updates like this it is becoming a VERY useful tool when designing in a manufacturing environment.