libLAS is a library that processes the LAS LiDAR format. It is now, apparently, available in the OSGEO4W repository. OSGEO4W is a set of applications and libraries compiled for Windows by the most awesome OSGEO project; it is a complete environment to work with many raster (OGR) and vector formats (GDAL). The packaging system also includes Python, which is great for geoprocessing scripts. It also includes QGIS stable and experimental. This OSGEO4W is the way to go if you're using Windows!
Anyway, libLAS as compiled with OSGEO4W can immediately process LAS formatted LiDAR data into OGR supported formats using las2ogr. For example, you could download LAS point cloud data and immediately get a GeoTIFF with all vertical reprojections applied. Neat-o.
Of course, if you don't want to try installing OSGEO, you could try one of their Live DVDs or VMWare images. But I highly doubt the LibLAS software has made it in version 4.01 (it was released August 26).
It is only a matter of time before libLAS and las2ogr makes it into OGR packages for OS X 10.6.
Happy geoprocessing and happy Halloween. It's back to constructing Mohr circles and plotting lines and planes on stereonets.