I would guess (but not bet money) that it was someone from EveryDevel or Blockstackers, and not a perl monk -- since technically, the shirts aren't really available (where's that web store? *hint hint*). I picked one up at lwce, I know at least one or two other monks did as well.

As a sort-of follow-up, I was wearing my PM shirt at a recent event and someone came up to me who actually knew what the site was. He wasn't a perl monk either -- which confused me greatly. My worldview does not include the scenario in which a person knows of PM and is not a registered user and regular visitor. It turned out that he was a friend of Chris diBona (visible in the random monk pic rotation). Minor mystery solved.

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