App Engine is amazing. A high scalability server with a pseudo
Content Delivery Network - provided by Google, so it's fast anywhere in the world.
Problem is : it supports JSP, Python, and Go by default.
Solution is :
http://quercus.caucho.com/ to use PHP (on top of Java).
It's amazingly fast (faster than plain vanilla PHP), with a few restrictions.
Import the lib, add the servlet and mapping to your web.xml, you're good to go.
But what if you want mod_rewrite?
That :
http://code.google.com/p/urlrewritefilter/
You still will only have "GQL" instead of SQL (unless you write
your own MySQL/GQL binding, which shouldn't be too hard
but might go against App Engine terms of service), and no write
access to the file system (which, once again, can be circumvented
using a GQL interface) by default.
But for the rest, you can now combine Java and PHP on one of
the most powerful web servers available to the public, for free.