Are there any Facebook employees/ex-employees here on HN? I've often wondered how many PHP developers they have on staff and how they manage deploying/integrating stuff in PHP for production.
http://developers.facebook.com/opensource.php
Particularly, Thrift is what they use to use PHP on the front end of the site to communicate to servers running C++ and Erlang environments. At least, thats what I've heard.
when i left in march, facebook had about 100 engineers writing primarily PHP code. the engineering team has continued to grow rapidly over the past few months so the number is probably close to 200 now.