Greg Lennon at Red Arrow Maps sent an email noting that over 100 independent US counties now have high-resolution LIDAR data available for free or at nominal cost, according the National LIDAR Dataset webpage on Wikipedia. This is in addition to the handful of states that have state-wide coverage.
The National LIDAR Dataset page was first created less than one year ago, and it has been growing steadily in both the number of counties listed with LIDAR coverage as well as in readership. It is a free community resource, and GIS professionals and others are encouraged to add data at any time.
The USGS CLICK Center for LiDAR Information Coordination and Knowledge is also actively involved in coordinating a US-wide effort to make the National LiDAR Dataset a reality.