MultiBinding is a must-have feature. It is used extensively by virtually ALL moderate-to-large size WPF application. I wonder that not only it has not been added yet, there's no mention of the feature even in the upcoming roadmap.
Please add support for MultiBinding if you want serious WPF developers to consider this tool.
Steve L commented
Yes, please! Multibinding is as essential as string, double, Binding, etc..
Very, very important. I use it everywhere in my WPF applications. Can't stress it enough.