During a Mobile World Congress press event on Sunday night, Nokia confirmed that it will release a lineup of entry-level smartphones based on Google's Android OS. Dubbed the Nokia X, this lineup will include three affordable models that come in a variety of familiar Lumia-like shapes, and feature a Windows Phone-like user experience, but can run Android apps.

"Today Windows Phone is the fastest-growing mobile ecosystem in the world, and we continue to see incredible momentum with our Lumia smartphones," Nokia Vice President Bryan Biniak said in a prepared statement. "Now, with the introduction of the Nokia X family of devices, we're delivering the same design, quality, and innovation Nokia is known to lower price points to capture the fastest-growing segment of the smartphone market."

As expected, the Nokia X lineup is technically an Android Open Source Project (AOSP) platform, meaning it does not offer Google services and apps, including the Google Play store for apps and content. This is the route that Amazon took with its Kindle tablets, but it requires the device maker to provide their own apps, services, and app store.

Related: "Nokia Worked on an Android Handset? Obviously!"

Nokia has ported a lot of their Windows Phone apps to the devices, and is of course bringing services such as HERE Maps and Nokia Music as well. For apps, Nokia X will provide the Nokia Store. Nokia notes that "the vast majority of Android apps can be published to the Nokia Store as is." The firm is providing a tool to help developers port apps that need more help. But a number of useful third-party apps will work on the devices immediately, including Facebook, BlackBerry BBM, Bubble, Picsart, Plants vs. Zombies 2, Real Football 2014, Skype, Spotify, Swiftkey, Twitter, Viber, Vine and WeChat, among others. And for the first time, BBM is also coming to Windows Phone, Nokia says.

Of course, the big controversy here is that Nokia is selling its devices business to Microsoft as soon as this quarter. Why would Nokia launch a new lineup of phones—the X line appears to sit logically between the current Lumia and Asha phones—at such a time? Nokia says that the X devices are priced to sell in emerging markets and that they will help drive users to Microsoft services for email, cloud storage, and more.

Microsoft, of course, knew this announcement was coming. But that doesn't mean it was happy about it.

"There are some things [Nokia does] that we are excited about, and other things that we are not so excited about," Microsoft's Joe Belfiore said Saturday at his company's Mobile World Congress press event.

The firm also issued an official explanatory statement, in which it reminded everyone that Microsoft and Nokia were still "two independent companies," in case that wasn't obvious.

"We're pleased to see Microsoft services like Skype, OneDrive, and Outlook.com being introduced on these devices," the statement notes. "[But] our primary smartphone strategy remains Windows Phone, and our core device platform for developers is the Windows platform."

In other words, Microsoft might not like it, but Nokia is free to do what it will ... for now. But I have a hard time imagining a Microsoft-controlled Nokia ever shipping these devices. In fact, I assume Microsoft is planning right now to morph the X lineup into low-end Windows Phone handsets instead. If there's anything Microsoft doesn't need right now, it's yet another platform.

Related: "In Blockbuster Deal, Microsoft to Buy Nokia"