I used a "alpha" Version at a wedding, it did just have a remote trigger and that was it. Using my canon Point-and-Shoot camera with CHDK, trigger via 5V on USB. I will attend two weddings this year, so i will bring this to those weddings also.
This setup will have a big red blinking button, noone will search "where is the button" anymore, and the setup should be in a box, where you just plug in and start the show.
Also it should have a display forwards, so that people see themselfs, and have a short 5 seconds to watch their work after the shot.