Steven Van de Craen's Blog : SharePoint 2007 B2TR: Using a Custom Data Source for Navigation: "I'm currently implementing a custom data source for my SharePoint 2007 Collaboration Portal. You can find a pre-release topic about this on MSDN here. Unfortunately this topic is not compatible with Beta 2 Technical Refresh so here are the updated instructions.
Instructions for Beta 2 Technical Refresh.
Create a folder MyCustomNavigation under C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\FEATURES\"... For a production server it is recommended to sign the assembly with a strong name and registering it in the Global Assembly Cache. Don't forget to update the web.config in that case !
P. Erol GIRAUDY