Can you play DC Universe Online on a PC and play with someone on the ps3

No they are not the same game and are different from when they are being developed. Games are software designed to work exclusively with the hardware they were developed for. PC games are only compatible with PC games if you can not play the game version in a PC why would you think they could play each other because they are both using a part of the internet. The PS3 only plays on the Playstation Network and the PC can not play a game on the Playstation Network. They are always different games that only have the same titles. It is not just DC Universe, but every PC game.