  Signatures of lensing of the cosmic microwave background radiation by
gravitational potentials along the line of sight carry with them information on
the matter distribution, neutrino masses, and dark energy properties. We
examine the constraints that Planck, PolarBear, and CMBpol future data,
including from the B-mode polarization or the lensing potential, will be able
to place on these quantities. We simultaneously fit for neutrino mass and dark
energy equation of state including time variation and early dark energy
density, and compare the use of polarization power spectra with an optimal
quadratic estimator of the lensing. Results are given as a function of
systematics level from residual foreground contamination. A realistic CMBpol
experiment can effectively constrain the sum of neutrino masses to within 0.05
eV and the fraction of early dark energy to 0.002. We also present a
surprisingly simple prescription for calculating dark energy equation of state
constraints in combination with supernova distances from JDEM.
