UML Can Be Useful
I have to agree with Nat Pryce here - UML does not prove that your software will work. You can’t find a bug in your UML and you can’t create UML that can be compiled and that an end user can test. Sometimes I think that is what attracts people to it! I said as much in my post on Effective UML (http://outofthetriangle.wordpress.com/2007/10/06/effective-uml/) as well as listing what you can do to make sure the UML you produce is useful.