Edit: Nevermind. I was confused when the article said, "Pennsylvania's Public Utility Commission recently allowed UberX to operate in the state, but not Philadelphia." I took that to mean they were not operating UberX in Philadelphia. But maybe it means they are? Illegally?
There is UberX in Philly now, although as far as I know there were no regulatory changes (and Black still operates legally). The PPA actually did a handful of "sting" operations against UberX drivers when the service started, calling an Uber and then impounding the vehicle (http://www.phillymag.com/news/2014/10/26/uber-philadelphia-u...).
As far as I am aware (I use uber quite a bit), Uber X is only available in the suburbs. In the city, it's not available; I've only ever gotten the Uber black sedans.
EDIT: This is no longer true, apparently my statement about using uber quite a bit is also no longer true.
