1. Open Visual Studio 2008 and create a Word 2007 addin

2. Add a New Item of type Ribbon (Visual Designer) to the project

3. Now you can drag and drop buttons and controls on to the Office Ribbon to your hearts content. This includes all of those funky looking controls you have been staring at in Office 2007 for the last year, like Gallerys, splitbuttons and button groups.

You can also add a XML based ribbon definition instead of a Visual Designer one if you prefer. In fact, you can build up your ribbon visually and then export it to XML.