This is a little geeky, but if you’ve ever wondered what “single sign-on” really means in the enterprise space, Unicon’s Andrew Petro has a great ten-minute YouTube video explaining the concepts, specifically as they are implemented in Jasig’s Central Authentication Service (CAS):
[youtube]http://www.youtube.com/watch?v=Ik_11Y17ASg[/youtube]
Nice, clear presentation in the video. A little more detail on the proxy server might have been useful but I can look that up easily enough.