The framework was first created by Jonathan ‘Peli’ de Halleux as a hobby project while studying for his PhD. Later Peli and Jamie Cansdale added support for MbUnit to Jamie’s NUnitAddin (later it would become the TestDriven.NET addin). After Peli’s departure to Microsoft in 2005 (working first as a SDET on the CLR and more recently in the Foundations for Software Engineering group in Microsoft Research) the project was opensourced under Andy Stopford.
The current lead of MbUnit, Jeff Brown, also leads the Gallio Project. Since Gallio is the foundation of MbUnit v3, many MbUnit committers also work on Gallio and vice-versa.
The projects regular commit members are listed here and here.
These are just a few projects and companies who are currently using MbUnit: