Show HN: Check-In App, using Twitter and text messaging

I built a little tool, which I thought HNers would find fun. You can play with it here: http://checkintext.appspot.com/ Follow the instructions at the top, and you'll appear on the page. If you're on a smaller screen, you might benefit from zooming out.

The story behind it is over here: http://www.ousbey.com/blog/check-in-app

Do let me know what you think!