Similar Project
I have found a similar project to mine from American International University-Bangladesh called Smart UML. Although the project is designed for Pocket PC the techniques they used to match shapes are similar to my inital ideas. They use a XUML (Xml for UML) file format, I have emailed the lead developer asked whether this is related to UML eXchange Format and about any problems that they had during the development.
http://smartuml.sourceforge.net/