I am not saying that as an attack to PHP (or a defense of NodeJS), I am writing PHP daily, but when it comes to real-time (at least WS systems), PHP would be my last resort, mostly because it lacks any real support for such things, you'll have to force your way in.
I guess we come back to _just because you can doesn't mean you should_. :)
Why? PHP works fine as a daemon, there are many servers written in pure PHP, as well as frameworks for "async" programming.