Cosmic microwave background, where next?

After the fundamental contribution of Cosmic Microwave Background observations to define what is now known as the standard cosmological model, what lies ahead for the field? Ground-based, balloon-borne and space-based experiments will observe the Cosmic Microwave Background in greater details to address open questions about the origin and the evolution of the Universe. In particular, detailed observations the polarization pattern of the Cosmic Microwave Background radiation have the potential to directly probe physics at the GUT scale and illuminate aspects of the physics of the very early Universe