Prior to this, all the user had to do was enter their Apple ID and password and they would be good to go, so we guess with the added layer, it would make things harder for non-authorized users to access your iCloud.com account.
It has also been observed that until the second step of the verification process is complete, all the web apps for iCloud will be on lockdown, save for the Find My iPhone feature which will remain enabled, presumably so that users can find their device in the event it goes missing and they need their verification code.
AppleInsider has since managed to confirm this new system, but it is unclear if Apple is merely in the testing stages or if they are planning on rolling out to the masses soon. However a report from MacRumors claims that Apple has since disabled the feature for accounts that could previously access it, suggesting that it might have rolled out a little earlier than expected.