http://www.webdigi.co.uk/blog/2009/run-php-on-the-google-app-engine/So all you need to use the GAE and run PHP
1) Register a free account.
2) Download this file to your computer.
3) Edit application XML tag in the file war\WEB-INF\appengine-web.xml to the name of the application you have registered.
4) Finally upload your application. I downloaded Google App Engine SDK for Java and use the following command in windows.
appcfg.cmd update C:\projects\phpwithjava\war
I wish i had some time to install and do some benchmarks to see what kind of computing power
youd be getting for free..