Alibre has completed porting their entire code to C#. Users would not be bothered with this since it is something internal and not visible or experienced by them. But the reasons for porting to C# are mainly to be able to add new features more easily, improve performance and UI, among other things.
Alibre Design 2011 now supports 64 bit natively. This gives it the ability to work with much larger models and increase performance significantly.
You can download a PDF listing the feature and development summary of Alibre Design from here.