Apple did not make a big deal about the Shift Key in the iOS keyboard at today's WWDC 2015 Keynote, but they have indeed changed the behavior of the keyboard significantly. Historically, the iOS keyboard has only shown capital letters, just like every physical keyboard in the universe. Some people, especially Android converts, have complained and Apple has changed it.
As you can see in the video above, the keyboard can now show lowercase letters when typing in lowercase. Is this a big deal? No, but a lot of people will welcome the change.