Android Pay is real, and it's going to power mobile payments across Android. But it's not so much an app or even user-facing feature, as a service that developers will be able to leverage as an API framework to build payments into their own apps.
[custom:mwc15] The news comes from none other than Sundar Pichai, Google's SVP of Product, at MWC 2015. He said that Google agrees with the general sentiment that mobile payments have reached a new level of importance this year, and that it makes sense to be able to carry your cards in the phone you're already carrying.
Google will be taking what's become standard measures for mobile payments, including tokenized card numbers for secure one-time transactions (if a retailer where you've shopped using Android Pay is compromised, the crooks get a one-time-use number that's no longer any good). Card data is stored locally, so you'll be able to use Android Pay even if you don't have a cellular connection available. In these ways it's much more like the Apple Pay system you'll find on the iPhone 6. There's no denying that the push that Apple and banks have put behind Apple Pay has lit a fire underneath the collective industry when it comes to consumer awareness of mobile payments.
The choice to go with an API means that Google's making it possible for other developers and manufacturers to build Android Pay more easily into their apps and systems. Google Wallet isn't even going away — it's going to leverage Android Pay as a payments source. Android Pay will work over NFC, and will eventually support biometric security measures (such as fingerprint scanning). As for the just-announced Samsung Pay for the Samsung Galaxy S6? That's something else entirely, Pichai said, but Google intends to work with Samsung to see how they can align the two products, but they're not looking to oust it as an option: "Users love choices."
We don't have an ETA for when we can expect Android Pay to be released, but we'd expect that we'll learn a lot more at Google I/O in May.