Yesterday, Microsoft made a landmark announcement that it would be licensing the Office 2007 UI to non-competing applications. They also released a 106-page specification that licensees will be required to follow. Now, the Office UI has been the benchmark by which applications have been designed for years, but in the past, Microsoft pretty much just looked the other way. Officially sanctioning the use of their research work is a bold move for Microsoft, whose ramifications should not be underestimated in the developer space.
My friend Tim Dawson has been re-creating Microsoft UIs in reusable packages for years (he had WinForms dockable menus long before Microsoft built them into .NET, and has the best WinForms window docking component on the market). He was one of the early adopters of the Office 2007 UI license, and his SandRibbon component is by far the easiest way to get jump-started on the Office 2007 UI. If you're doing .NET development and want to use the Ribbon, then you should take a look at the hard work Tim has done to comply with many of the guidelines as possible.
DISCLAIMER: This is not a paid endorsement. I am recommending this solution of my own volition, because I've tested several different Ribbon components and I think this one is the best.