Brian Dorsey and I built a tiny new app for the iPhone called WhereBeUs. It’s available in the App Store today!

Wondering when your friends are going to show up for coffee? Pop open WhereBeUs and you’ll see exactly where they are right now.

WhereBeUs Screen Shot

There are similar applications, but Brian and I think we’ve built the simplest, most minimal such application. WhereBeUs gets your friends from Facebook and Twitter, so there’s no need to create new accounts or set up new friendship connections. After you’ve signed in, you’ll instantly see your other WhereBeUs-using friends.

This was a fun side project. It took a few weeks of spare time to build. We’ve decided to make it free and open source. The code is available on GitHub. Right now the front-end is iPhone only and the back-end is App Engine + Django. Despite the apparent simplicity, we’ve done a lot of work to ensure that the application scales to millions of users and tens of thousands of friends per user. We hope that our developer friends will contribute cool new features. We’re especially excited about building cool new Android and Palm Pre front-ends.

So: check out WhereBeUs today and let us know what you think!