By Andrew Brown, Software Engineer at ArtistSignal
After asking the question, I dug around and did a little research, and I'd like to answer it with: it's quite likely.
I was exploring the items included in the client and spawning them to see in-game, and happened across a Staff of Herding (herding cows?) with the description "Only one bovine in all of Sanctuary could possibly have a use for this."
Upon closer inspection, I also found a Nightmarish Staff of Herding and a Hellish Staff of Herding, which are most likely references to the different game difficulties.
And if that wasn't enough, I also found a seemingly-useless item called Wirt's Bell, with an unattributed quote in the description: "When the demons come, close your eyes and ring this... it takes you far, far away...", which, if I had to guess, is a double-reference to Wirt's Leg in Diablo II and the Red Portal that teleported you to the cow level in Diablo II.
Edit: I've also found an Infernal Staff of Herding.More questions on video games: