Here's a really entertaining, and informative article about the behind-the-scenes workings of Kerberos... well, as entertaining as any article about Kerberos can be.

http://web.mit.edu/Kerberos/dialogue.html

Honestly, though, it really is pretty entertaining, and it does a great job of explaining what is going on in a step-by-step way... and why all of it is going on. A good, short read.

Here is an Apple-produced video that shows all of this behavior graphically: files.me.com/overstim/75czx8.mov