I stayed in a hotel this Shabbos in a small Jewish community near the shul. These days it is a big problem to stay in a hotel for Shabbos because almost all hotels have switched over to electronic keys. Electronic keys use electricity and therefore are prohibited to use on Shabbos for whatever reason electricity is prohibited (there are a number of reasons given including the opinion of the Chazon Ish that creating a circuit is Boneh min hatorah, RSZA holds that there is no issur whatsoever however, it is prohibited based on minhag). The bottom line is we assume that electricity on Shabbos is prohibited at least m'drabbanon.
The advice that I got was to tape up the lock and leave the door unlocked on Shabbos when I go out, I did this and while it worked it made me very nervous. R' Willig told me that if you get locked out you can ask a non-Jew to open it as it is a shvus d'shvus b'makom kitzva.
This illustrates the problem that electricity poses for us and is going to pose for us in the near future. Everything is going electronic. Soon it will be very hard to find anything that doesn't have some kind of electronic sensor on it. If you go to a hotel you can see some of them for example:
Electronic keys
Motion sensors which shut off the lights and air conditiong if there is no movement
Faucets that go on and off based on motion sensors
Toilets with sensors
Automatic doors
Security cameras
...
Household appliances are changing as well. New refrigerators all have sensors that are put into action when you open the door etc. (even if you tape down the light switch). Modern burglar alarms have sensors on the door and register when the door opens even if the alarm is off. There are surveillance cameras everywhere.
The point is that electronics and sensors are becoming ubiquitious, they are going to be everywhere. It will soon reach a point that we will not be able to do anything without causing some reaction in some sensor.
The question is what will the reaction from the poskim be? RSZA opinion that there really is no issur seems to be very well reasoned and I believe is generally accepted. The question is will anyone have the courage to run with it and say that in the modern world where circumstances have changed we need to allow certain things (like electronic locks, refrigerator sensors etc.) The fact is that in the next 10 years the incandescent light bulb will go the way of the dodo which will remove the only issur doraysa related to electricity. I know that there is a very fine line it is clear that we don't want people using computers, tv's, mp3 players on shabbos, on the other hand we are rapidly reaching a point where we will be unable to do anything on Shabbos in a modern home. The poskim need to come up with some kind of balance, given what is going on in the Jewish world I am not optimistic.
