  We review recent results for the chiral behavior of meson masses and decay
constants and the determination of the light quark masses by the RBC and UKQCD
collaborations. We find that one-loop SU(2) chiral perturbation theory
represents the behavior of our lattice data better than one-loop SU(3) chiral
perturbation theory in both the pion and kaon sectors.
  The simulations have been performed using the Iwasaki gauge action at two
different lattice spacings with the physical spatial volume held approximately
fixed at (2.7 fm)^3. The Domain Wall fermion formulation was used for the 2+1
dynamical quark flavors: two (mass degenerate) light flavors with masses as
light as roughly 1/5 the mass of the physical strange quark mass and one
heavier quark flavor at approximately the value of the physical strange quark
mass.
  On the ensembles generated with the coarser lattice spacing, we obtain for
the physical average up- and down-quark and strange quark masses
m_ud(MSbar,2GeV)=3.72(0.16)_stat(0.33)_ren(0.18)_syst MeV and
m_s(MSbar,2GeV)=107.3(4.4)_stat(9.7)_ren(4.9)_syst MeV, respectively, while we
find for the pion and kaon decay constants f_pi=124.1(3.6)_stat(6.9)_syst MeV,
f_K=149.6(3.6)_stat(6.3)_syst MeV. The analysis for the finer lattice spacing
has not been fully completed yet, but we already present some first
(preliminary) results.
