iTunes Pass involves point-of-sale, your iTunes/App Store account and Passbook. All these together could create the formula for a mobile payment system. But they don't. At least not yet.
As it stands today, iTunes Pass is simply a way to add money to your iTunes/App Store account at an Apple Store. This accomplishes the same thing as redeeming a pre-paid gift card into your account. The biggest benefit of being able to do this at an Apple Store is that it adds the ability to use cash to load up your iTunes/App Store account. Combine that with the new Family Sharing in iOS 8 and perhaps we can see where Apple's going with this, at least in the short term.
Does this mean Apple won't launch their own mobile payments system? No. But it doesn't mean they will, either. More than likely this is just Apple solving a simple problem. But as we've often seen with Apple, the lessons learned solving one problem will not necessarily be ignored when another, similar problem is up for discussion.
Time will tell.
For now you can follow our instructions for adding iTunes Pass to your Passbook. You know, just so you have it all set up.