Send a tweet to your office door [Hands On]

Here at IEEE Spectrum, staffers routinely put Post-It notes on their doors and cubicles to let colleagues know they're out. But you can't slap a note on your door if you decide to work at home at the last minute-which, as I learned this winter, happens quite often when you have a very pregnant wife about to go into labor any instant. That's why I set out to replace those yellow sheets of self-adhesive stationery with something less, uh, analog-something that would allow me to post the updates electronically. An idea then popped up in my head: Twitter for my door.