Tom Miller has been with Microsoft for a full decade. He specializes in bringing together managed code and gaming. He wrote and supported Managed DirectX, and for the past few years, he has been largely responsible for implementing the framework (graphics, audio, input, storage, and other core features) included in XNA Game Studio products. He currently works for Microsoft Game Studios.
Dean Johnson joined Microsoft in 2006 and helped launch the XNA Creators Club pipeline allowing hobbyists and independent developers to release their games on the Xbox LIVE Indie Games Marketplace. He currently is a Lead Software Development Engineer working on the XNA Game Studio product team.
Both authors actively blog and participate in game development conferences.