This article from 2008 on the old bnet publications page was a very fun read long ago (Life on the Bungie Farm: Fun things to do with 180 servers and 300 processors - Luis Villegas, Sean Shypula)
"Even if your users are programmers, they still don’t want to understand how the system works"
Maybe I'm not typical, as I'd love to know more about the system and how it is evolving.

This more recent photo from a Penny Arcade tour earlier this year showed a dark, intriguing view of the server room.

There is likely alot that you wouldn't want to show and tell, but seeing even a little more would be exciting. Especially with the revelations you guys have made in rendering, custom light mapping, shading, visibility, plus continuing advancements with particle effects, and simulated physics, etc.

In the IT world, get your hands on as many things as you can. Don’t just install something and say “Yay, I know this now.” Beat the crap out of it. Break it, wipe it, and start over. Do that a couple dozen times, and then it can go on your resume. Breadth and depth of knowledge is what it’s all about.

Iterate, iterate, iterate, keep at it