The current procedure requires the Gate Agent to knock on the door before attempting to open it. At the sound of the knock, the F/A ensures that the slide is disarmed and gives a 'thumbs up' signal to the Gate Agent who then opens the door. This system gets two people involved and introduces a 'Challenge and Response' type checklist that is traditionally used in cockpit ops. The GA's knock (challenge) requires the F/A to recheck the door disarmed and give a thumbs up (Response).

Let's face it, we all make mistakes and it's very easy to leave a door armed when it's a one person operation. One of the reasons that I would always advocate a two person flightdeck regardless of the automation is that there's another person there to catch my mistakes (and believe me, I've made some doozies only to have the other guy save me). This door procedure gets one more person involved and prompts the F/A to recheck the slide....that's a good thing and the proof is the reduction in blown slides.