from their website http://www.pinballarcade.com/
(this info is for the andriod version, but should be the same all around) :
Each month, regular updates will add classics like Monster Bash®, Medieval Madness®, Creature from the Black Lagoon®, Funhouse®, Attack from Mars®, Black Knight®, Space Shuttle®, Pin•Bot®, Circus Voltaire®, Big Shot®, (and many others for years to come!)
Looks like PinMAME for PC or a couple of the pinball emulators avail on PSN already.
I'd get it, if its not more than $15..
Wonder if they charge you for the new tables... or if its a monthly sub fee or something.