Overview of Microsoft Windows SharePoint Services
Using Windows SharePoint Services to Manage Visio Drawings
Accessing Documents Stored on a SharePoint Site from Visio
Viewing a SharePoint Task List as a Visio PivotDiagram
Viewing a SharePoint Task List as a Visio Flow Diagram
Viewing a SharePoint Calendar List as a Visio Diagram
Techniques for Sharing Visio Data from a SharePoint Site
http://msdn.microsoft.com/en-us/library/bb229690.aspx#Visio2007IntegratingSharePoint_TechniquesforSharingVisioDatawithSharePoint