a) it's fun to do that sort of geeking,
b) Lori wasn't home, so I was fairly idle anyway, and
c) I feel that I've asked so many people for help developing my own campaign that I owe a karmic debt to try to help others.
It was fun. I picked feats and magic items for some of his NPCs, and I suggested a challenge for the PCs to face. It ended up being kind of a nifty challenge, if I do say so myself--I don't want to give any details, since I think some of his players read my journal, but I look forward to hearing how they deal with the challenge.
Planning out GMing is so much easier with a friend to bounce ideas off of. Maybe I should try applying Extreme Programming principles and organize a game with two GMs and N players.