  We present adaptive optics imaging from the NIRC2 instrument on the Keck-2
telescope that resolves the exoplanet host (and lens) star as it separates from
the brighter source star. These observations yield the $K$-band brightness of
the lens and planetary host star, as well as the lens-source relative proper
motion, $\mu_{\rm rel,H}$. in the heliocentric reference frame. The $\mu_{\rm
rel,H}$ measurement allows determination of the microlensing parallax vector,
$\pi_E$, which had only a single component determined by the microlensing light
curve. The combined measurements of $\mu_{\rm rel,H}$ and $K_L$ provide the
masses of the host stat, $M_{\rm host} = 0.426\pm 0.037 M_\odot$, and planet,
$m_p = 3.27 \pm 0.32 M_{\rm Jup}$ with a projected separation of $3.4\pm
0.5\,$AU. This confirms the tentative conclusion of a previous paper (Dong et
al. 2009) that this super-Jupiter mass planet, OGLE-2005-BLG-071Lb, orbits an
M-dwarf. Such planets are predicted to be rare by the core accretion theory and
have been difficult to find with other methods, but there are two such planets
with firm mass measurements from microlensing, and an additional 11 planetary
microlens events with host mass estimates $< 0.5M_\odot$ and planet mass
estimates $> 2$ Jupiter masses that could be confirmed by high angular
follow-up observations. We also point out that OGLE-2005-BLG-071L has separated
far enough from its host star that it should be possible to measure the host
star metallicity withspectra from a high angular resolution telescope such as
Keck, the VLT, the Hubble Space Telescope or the James Webb Space Telescope.
