On the Google Developers Blog there's a new post from Keith Casey showing you how to get started with Twilio on a Google App engine, PHP-based application. It requires the use of the latest Twilio helper library, so be sure to upgrade.
I’ve wanted to explore Google App Engine for years. Between its SLA, automatic scaling, and queuing system, it has always been compelling. Unfortunately, since my Python skills are somewhere between “Hello World” and “OMG What did I just do!?” I decided to save myself the embarrassment. When Google announced PHP support for App Engine, I was both ecstatic and intrigued about what might be possible. To get something running in just a few minutes, I decided to use our Twilio PHP helper.
He walks you through the full process - setting up an App Engine account and instance, using the a href="http://www.twilio.com/docs/libraries">helper library and how you'll need to configure your routing for the files in your application.