Note: The Map Room has a good wrap-up of related maps, updated almost daily.
The Haiti earthquake, 7.0 magnitude, struck about 10 miles south-west of Port-au-Prince, was quickly followed by two aftershocks of 5.9 and 5.5 magnitude. The automatically generated Preliminary Earthquake Report from the U.S. Geological Survey includes many maps, including a shake map (top) and a look at historical seismicity in the area (bottom). More maps here.
They say: The January 12, 2010, Haiti earthquake (7.0 magnitude) occurred in the boundary region separating the Caribbean plate and the North America plate. This plate boundary is dominated by left-lateral strike slip motion and compression, and accommodates about 20 mm/y slip, with the Caribbean plate moving eastward with respect to the North America plate.
The location and focal mechanism of the earthquake are consistent with the event having occurred as left-lateral strike slip faulting on the Enriquillo-Plaintain Garden fault system. This fault system accommodates about 7 mm/y, nearly half the overall motion between the Caribbean plate and North America plate. More here.
And from NASA Earth Observatory, a map showing the topography and tectonic influences in the region of the earthquake.
The NYTimes mapping division has a useful before and after tool using satellite (GeoEye) imagery; several key buildings are highlighted.