The Vancouver-based BigPark is a company that bills itself as an "an interactive online entertainment company". Not much else is known about BigPark except that its members are said to have produced franchises such as Need for Speed and SSX.
Microsoft and BigPark will be collaborating on an Xbox 360 exclusive title that will likely be revealed at E3. Right now we have no idea about what it could be, but BigPark states on their official website that their mission is "To expand gaming audiences around the world and bring them together through accessible and highly entertaining interactive experiences."