Earlier this year Ubisoft released Assassin's Creed 2 with DRM that required you to be online to play the game. Even if you only wanted to play single player you still had to have an internet connection for the game to load. If you lost your internet connection while playing the game you would be kicked off without the chance to save.
Shortly after the game was released Ubisoft's authentication servers went offline and no one could play the game. They were left with nothing but an apology from Ubisoft a few days later. Shortly after that they released a patch that would save your spot if you lost your internet connection rather than forcing you to go back to your most recent save. They still won't let you play the game though without a connection.
It seems Capcom, the creators of Final Fight:Double Impact, have taken a page out of Ubisoft's DRM handbook. They are requiring that you be signed into the Playstation Network to play the game. The Xbox 360 version will allow you to play online or offline.
If you try to play the game on the PS3 without a connection to PSN you get an error that states "Sign into PlayStation Network. (80029516)"
Joystiq posted a response a user claimed to have received from Capcom and posted it in the IGN forums, "Yes, there is DRM," the admin confirmed. "This was employed to combat the rampant 'PSN Sharing' that has been going on over the last year. We're sorry that your family cannot play the game on their individual accounts (same console). This is a limitation of the Sony network." The message goes on to say that Double Impact's DRM is a trial to "evaluate impact" of the PSN sign-in requirement, which seeks to limit access to the game to the PSN account that purchased the title."