The following accounts have been compromised:
I don't know the exact method by which they were compromised, but I would guess weak password recovery questions or a flaw in the password recovery question/answer system.
I have updated the forum to the 1.1.16, which is the latest release of SMF 1.1.
I have also removed "ask me my question" method of password recovery.
You can now only recover your password via email.
UPDATE: I have unbound the Blockland keys from these accounts so their owners can create new accounts.