Steam Guard already exists via PC; if you try to sign into your Steam account on a new computer and you have Steam Guard on, you’ll get prompted to input some information Valve sent to you via email. Now, though, Valve is testing Steam Guard through its mobile application in the form of the Steam Guard Mobile Authenticator.
It’s in beta right now, but you can sign up by joining the beta group for the application and hope Valve picks you out of the list.
If you’re signing onto Steam from a new computer, you’ll be able to pull codes using the application to verify yourself, rather than checking email. Your phone number will also be able to be used as a way to recover your account in the case of a lost or hacked password.
With just about every business out there getting hacked and vulnerabilities like Heartbleed compromising countless passwords, two-factor authentication is the best way to protect accounts from malicious activity. Even with a weak password, your account still requires your explicit permissions. Whether it’s Steam or Gmail or whatever else, two-factor authentication should be enabled for every account it’s available for.
While it might be quite a while before Steam has the mobile authentication feature of its app rolling out to the public, it’s still a good step forward.