CBS2 Morning Show
Usage quickly spiked after these stories ran -- there are about 1200 people following the Metra feeds at this point. The only problem was that it was running on my personal computer. If I needed to reboot or experienced an internet outage, no updates were posted.
In an effort to make the service more robust, I decided to port to Google App Engine, which allows developers to create applications that run on Google infrastructure. App Engine has been around for about a year, but my Twitter app couldn't run there until a couple weeks ago, when the App Engine team unveiled Scheduled Tasks. This feature allows me to run my regular scans over Metra's delay info, and post the relevant material to Twitter.
All in all, porting to App Engine was a great experience. It's a very straightforward, developer-friendly environment, and I had fun doing it. And now I can turn off my computer again. :P