About a week ago Microsoft published the XML Schema Definition (XSD) files for the Microsoft Visio 2010 XML Drawing (.vdx) format. This schema is also known as DatadiagramML.
This should make it alot easier to use the visio file to generate code based in the visio file.

The DatadiagramML Schema for Visio 2010 consists of three .XSD files:

• visio.xsd is the core schema used by Visio 2003 and later
• visio12.xsd is the set of extensions used by Visio 2007 and later
• visio14.xsd is the set of extensions used by Visio 2010

More information about the schema is available in the Visio 2010 XML Schema Reference on MSDN.

This tool makes contenttype development a lot easier.

Click the contenttype together in MOSS and copy the xml from this tool into your sharepoint solution.

This tool works with SP2010 beta.

http://www.codeplex.com/MOSS2K7CTypesViewer