Valve Steam Guard officially launched
After a few weeks that has been in beta testing, Valve has today officially launched the service called Steam Guard for digital download platform games. With Steam Guard all users may wish to block their accounts on a single PC, so any attempt to access it from another computer will need a code (which users will have).
Steam Guard is highly secured, even Valve boss Gabe Newell confidently shared his Steam password openly at Game Developers Conference.
Note that this system only works with the second generation Intel Core processor and Intel Core vProT, which have the Intel Identity Protection Technology.
You can read the official FAQ here.