The League of Legends staff posted a notice up on their site recently stating that data on their EU West, EU East and EU Nordic databases had been compromised by some unauthorized folks. Details accessed include email addresses, encrypted passwords, encrypted secret questions, summoner names, dates of birth, and a few real names. No payment or billing information was accessed in the breach.
The League of Legends crew were unusually open about their whole process, which is refreshing considering every other company put in this situation has been quite guarded and distant after their security compromises. Riot Games already sprung into action fixing the exploited hole, emailing all affected players, implementing new security measures and continuing the monitor the situation.
Sad to say but we should all be used to the protocol now: change your passwords, mind what emails you receive and send, and cancel your credit cards if you feel like you have to. Godspeed and such.