[ewjordan]

Absolutely, though I'd warn that if you naively use PHP and a default setup (Apache with default settings for PHP or something like that), you're probably not going to serve as much traffic per server as a naive Python or Ruby setup will get you. You have to tune your way there, and it can be a bit of a process, but it's definitely possible, and there's nothing very subtle about it.

One of the biggest problems with PHP, IMO, is that most of the code you'll find online is extremely old, and probably will give you terrible advice, using old deprecated mysql libraries, etc.