Hi Jeff,
When you are creating the data connection to submit the form to the sharepoint library, On the third dialog of the wizard when you specify the url for the SharePoint Library, there is a second text box called Filename, you can put an xpath expression in here that uses some of the fields in the form to create an unique name. You can use the concat function to concatinate multiple fields together
e.g. concat("Proposal", <field1>, <field2>)
You can also provide an OnSubmit or OnSave handler and set the name of the file in code. There is an example in "Developing Solutions with Microsoft INFOPATH" by Patrick Halstead and others. Check out chapter 10, Uniquely Naming the Form.
Hope this helps.
Stephanie
Stephanie Cantwell / Test ManagerQdabra® Software / Streamline data gathering to turn process into knowledge