Valve is on guard

On GDC11 Steamworks represented it's brand new account security system - Steam Guard.

The new features offers the ability to link account managment to specific PC, and without the owner of account you could not chang account setting on anothers PCs without approval."With Intel's IPT and Steam Guard, we've taken a big step towards giving customers the account security they need as they purchase more and more digital goods." said Valve President Gabe Newell.  Users will also be informed if attempts to access or modify account settings have been made from non-authorised computers.