Nick
Favorite Answer
Take a look at their careers section on their website.
Or make your own games, and sell them on PlayStation Network, using the miniS kit and developer program. It isn't cheap though, but if you make a catchy game, you could be in business for yourself, and choose for yourself which direction game design goes. You might not make first party Sony games, but loads of great games aren't made by Sony, but by their partners (like Capcom, Namco, and Rockstar)
Albo
First you must annihilate Sega, make sure all the woman and children are killed. Then they shall see If you are worthy enough to be their game designer. Remember, Sega Is not a force to be reckoned with, there power Is still strong. Good luck. :)
meanddave
look them up--they should have a contact us number on the web site----ask them what u need to work4 them