Originally Posted by Why

last i knew yahoo runs on LAMP or similar stack, as does Flickr. Facebook is partially written in PHP but i think they port it to some type of C using HipHop. Either way, anything is possible, no matter which way you go. it does seem that large institutions like closed source for whatever reasons, educational facilities tend to be heavy on the CF also. there are many enterprise level apps written in all kinds of strange languages... there are more then just those two to look into, if you a fan of using the right tool for the right job.