  The recent advent of laser guide star adaptive optics (LGS AO) on the largest
ground-based telescopes has enabled a wide range of high angular resolution
science, previously infeasible from ground-based and/or space-based
observatories. As a result, scientific productivity with LGS has seen enormous
growth in the last few years, with a factor of ~10 leap in publication rate
compared to the first decade of operation. Of the 54 refereed science papers to
date from LGS AO, half have been published in the last ~2 years, and these LGS
results have already made a significant impact in a number of areas. At the
same time, science with LGS AO can be considered in its infancy, as astronomers
and instrumentalists are only beginning to understand its efficacy for
measurements such as photometry, astrometry, companion detection, and
quantitative morphology. We examine the science impact of LGS AO in the last
few years of operations, largely due to the new system on the Keck II 10-meter
telescope. We review currently achieved data quality, including results from
our own ongoing brown dwarf survey with Keck LGS. We assess current and
near-future performance with a critical eye to LGS AO's capabilities and
deficiencies. From both qualitative and quantitative considerations, it is
clear that the era of regular and important science from LGS AO has arrived.
