There is a comprehensive overview article on LIGO that just appeared. It's 25 pages long, and I think the first few pages are just the listing of all the authors alone! :)
B P Abbott et al Rep. Prog. Phys. v.72, p.076901 (2009).
Abstract: The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) of astrophysical origin. Direct detection of GWs holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black holes and neutron stars and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech–MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than one part in 10^21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on GWs from a variety of potential astrophysical sources.
I can't think of a more complete and up-to-date article on LIGO than this at the present moment.