  Semileptonic, B --> pi l,nu, decays are studied on the MILC dynamical
configurations using NRQCD heavy and Asqtad light quarks. We work with light
valence quark masses ranging between m_s and m_s/8. Preliminary simple linear
chiral extrapolations have been carried out for form factors f_para and f_perp
at fixed E_pi. The chirally extrapolated results for the form factors f_+(q^2)
and f_0(q^2) are then fit to the Becirevic-Kaidalov (BK) ansatz. Preliminary
estimates of the CKM matrix element |V_{ub}| are presented based on the
recently published branching fractions for B exclusive semileptonic decays by
the CLEO collaboration.
