R.J. Bouwens (UCSC), G.D Illingworth (UCSC), P.A. Oesch (ETH Zurich),
and the HUDF09 science team

The new WFC3/IR instrument on HST enables us to survey the sky in the
near-IR 40x more efficiently than ever before -- permitting us to make
enormous strides in our searches for z>=7 galaxies.  Already deep,
wide-area observations exist over some ~52 arcmin**2 in the HUDF09 +
ERS fields.  With these data, we have been able to select some 40+ z~7
galaxy candidates, 10+ z~8 galaxy candidates, and even some possible
z~9 galaxies over a 3 magnitude range in luminosity -- adding
significantly to the ~20-30 z~7 candidates known prior to WFC3/IR.  In
this presentation, I will summarize the constraints we are able to set
on the UV LF at z~7, z~8, and z~9 and its evolution to z~4 -- using
current and past data -- discussing early galaxy build-up in the heart
of the reionization epoch.