They will ID you when you purchase the tickets, and you will need an ID for every member of your group for whom you're buying tickets (except for child tickets, where they'll take your word for it). For example, I can't go up with my FL ID and purchase six FL resident tickets. I have to have six valid FL resident IDs, and they will put those six names on the tickets.
To my knowledge, they do not regularly ID at the gates, but if the biometric scan doesn't work properly, or if they're doing a spot-check, you could well be asked for ID.
