PHP is very, very hard to scale. Facebook goes through a lot of crap to make it work. Django would be easier, and RoR is a bit harder. All this fades away if

PHP is very, very hard to scale. Facebook goes through a lot of crap to make it work. Django would be easier, and RoR is a bit harder. All this fades away if you go with something like Microsoft Azure which just automagically handles everything for you. I like python, so, I would go with Django.