The latest release of NCrunch now features support for MbUnit, XUnit and MSTest (adding to the existing support for NUnit and MSpec). Further more the MbUnit and XUnit support is powered by Gallio.
The support for this started with a conversation between me and Remco Mulder (the author of NCrunch) at SC2011 back in May and continued over email as Remco integrated NCrunch and Gallio. This was a challenging integration and Remco worked hard to overcome many of the challenges, as a result he is also contributing code back to the Gallio code base.
It is great to see NCrunch join the family of third party tools that now support MbUnit.