Eve Online, one of the more well known MMORPGs around, recently had a security breach. It seems that the full source code for the game client has been made available through torrents and other avenues, much to the chagrin of the management and developers of CCP. There's an interesting conversation between the supposed thief and a developer for the game, well worth the read. What's more interesting is CCP's reaction, who is choosing to sensor discussion related to the source leak as well as using torrents to harvest IPs and match them to player accounts, later banning the accounts.
Source code leaks can become huge scandals, especially when the culprits are narrowed down and finally caught. Such is always the case with software that companies wish to protect, such as Valve leaking Half Life 2, Cisco's code or Microsoft losing the Windows source code from years ago.