  We report results for the interaction measure, pressure and energy density
for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In
our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$
improved staggered quark action for lattices with temporal extent $N_t=4$ and
6. The heavy quark mass $m_s$ is fixed at approximately the physical strange
quark mass and the two degenerate light quarks have masses $m_{ud} =0.1m_s$ or
$0.2m_s$. The calculation of the thermodynamic observables employs the integral
method where energy density and pressure are obtained by integration over the
interaction measure.
