Other than bypassing single user mode, I haven't heard anything that would indicate an OF password is set. Still, you really ought to try to find out if one is.
Try this:
Boot up holding down Command-Option-O-F to go to the Open Firmware prompt. Type:
> reset-nvram
If it asks for a password, you've got an OF password you need to defeat. Otherwise, forget the OF password part.
If you aren't asked for a password, type:
> reset-all
Your Mac will reboot. Otherwise, just reboot it with the three finger salute and call it a day. Then follow Tom's suggestion with regard to clearing the OF password.
Peace,
Drew