Following on from my blog about the Microsoft Visio Viewer, I am delighted that Microsoft have published a developer reference for it (long overdue, but very welcome). See the MSDN pages at http://msdn.microsoft.com/en-us/library/cc297217.aspx and Visio Insight blog http://blogs.msdn.com/visio/archive/2009/01/14/developer-reference-for-visio-2007-viewer-released.aspx