It is hard to say when Microsoft might actually reveal the new VR headset and technology, but it would seem that GDC or E3 would be the likely events to see it introduced. We do know that Microsoft is targeting 2015 to move the VR headset into mass production and it is thought that we will see versions for both the Xbox One and PC. Though we expect the PC version to come a little after the Xbox One version.
Rumor has it that the same development team that worked on the Surface tablet are the team that has taken on this project as well.