• Microsoft.com: Adding Custom Icons to Windows Movie Maker – …attach custom icons to your custom effects and transitions for Windows Movie Maker. These icons are created as a resource file in a C++ project and compiled into a DLL. – vidding. wmm2.
• Microsoft.com: Creating Custom Effects and Transitions in Windows Movie Maker – …effects can be created with an XML file that modifies the supplied effects or transitions, or can be built from scratch using C++ and the Windows Media Transforms supplied by the Microsoft DirectX Media SDK. – vidding. wmm2.
• Dividing a Complex Project into Sub-Projects – PapaJohn’s Newsletter Archive – …even with a powerful and well tuned computer, [wmm2] has a memory-related constraint […] you might have to bite the bullet, divide your project into sub-projects, and then add the pieces together for your final movie. But how??? – vidding. wmm2.
• Text Clips(Titles and Credits) – PapaJohn’s Newsletter Archive – …treat clips with text more generically. The same clip can be used at the beginning of a video, at the end, in the middle, or over other clips. – vidding. wmm2.
• Custom Titles & Credits – The new customization feature allows the users to overcome many technical limitations in Movie Maker for example exact placement of text and overlaying a transparent image as a logo. || A tutorial on an otherwise-undocumented feature. – vidding. wmm2.
• Download details: Samples for Custom Effects and Transitions in Windows Movie Maker 2 – Download documentation and code samples for creating custom effects and transitions in Windows Movie Maker 2. – vidding. wmm2.

(Update via Postalicious.)