Answering questions after today's Facebook Home event, Mark Zuckerberg was full of praise for Google's smartphone platform. "We think that Google takes their commitment to openness in the ecosystem really seriously," he said, regarding the possibility Google might try to lock out Facebook. Google, he said, was aware of Facebook's work, although wasn't a partner like a host of other industry players. "I actually think this is really good for Android," he added, setting up a gentle dig. "Most app developers put most of their energy into iPhone."

Meanwhile, Zuckerberg confirmed that Facebook Home is essentially an end-run around Google's services wherever they compete directly with Facebook's, with the ultimate goal of capturing more dollars. Home puts Facebook's social updates, Facebook's contacts, Facebook's messaging service, and crucially, Facebook's advertising directly on an Android user's home and lock screens. That's a much more direct attack on Google's business.

"With phones, there’s no room for a right-hand column of ads. That forced us to think about what the business looks like on mobile."

"With phones, there’s no room for a right-hand column of ads. That forced us to think about what the business looks like on mobile," Zuckerberg tells Wired's Steven Levy in an interview released today. At the event, he fielded a question: "We may see ads in cover feed?" Zuckerberg: "Yup!" This is targeted, full-screen, push advertising in your pocket when Google is still selling banner ads inside free apps. Facebook is squatting on prime Android screen estate. How does this not drive Google's Larry Page completely insane?

Google's official position on Facebook Home is diplomatic. “This latest collaboration demonstrates the openness and flexibility that has made Android so popular," a spokesperson told VentureBeat. "And it’s a win for users who want a customized Facebook experience from Google Play — the heart of the Android ecosystem — along with their favorite Google services like Gmail, Search, and Google Maps.”

This is important, because it reveals the territory Google is determined to defend. Facebook Home might seriously skin Android's user interface, but it doesn't cut out Google's core the way Amazon did with the Kindle Fire. Home doesn't promote Graph Search over web or local search, Facebook Messages over Gmail, or Facebook's App Center over Google Play. Facebook is pushing the boundaries, but it's also playing within the lines.

And for now, it doesn't have to play outside them. Facebook Home already inverts the system-level relationship between the social network and the launch screen. It already strips away nearly all of the chrome and UI features that make Android look like Android. Facebook just put the entirety of the core Android experience inside a blue-tinted, ad-sponsored wrapper, and then hid the wrapper as an app inside Google's own store.

Facebook just put the core Android experience inside a blue-tinted, ad-sponsored wrapper

Now, to be fair, Facebook Home does extend the functionality of Android in terms of notifications, multitasking, and messaging. It solves real problems, and adds real value to an already open, customizable platform. But we've seen this story play out before. Remember Google Toolbar? Before search, autofill, pop-up blockers, and webapp launchers were built into web browsers, there was Google Toolbar, offering all of those things as part of Firefox and Internet Explorer. Eventually, though, Google added more and more layers and extensions into the browser, growing along with its suite of web applications, including a personalized "Home" page incorporating news feeds and email updates. Finally, tired of being bound to another company's update schedule and codebase, Google built its own web browser and bought its own mobile operating system.

Google could still move fast, break things, and one of them will be Facebook's skin

Likewise, Facebook can and will continue to iterate to bring more of its features into Home, going deeper and deeper into the OS to do so. "I think this can start to be a change in our relationship that we have with these computing devices," Zuckerberg said today, touting the built-in ability of Android for software developers to extend it without limit. "We just think about it as software," Facebook Home product manager Adam Mosseri told The Verge, when asked about the dividing line between Facebook and Android on a Facebook Home device. And it may all just be software. But now Facebook is stuck with Android's update schedule and fragmentation. The company can try to control that somewhat by working directly with manufacturers, but so long as Facebook doesn't fully control the operating system, Google could still move fast, break things, and one of them will be Facebook's skin. Amazon didn't fork Android for the Kindle Fire because it's fun.

Google is Facebook's model, the other great web-first software company of this century, run by engineers and supported by advertising. Neither were the first of their kind; they were the companies who won, and soon looked for other worlds to conquer. They're the two consumer software companies that most quickly learned that data, not discs or downloads or even dollars, is the real currency of the 21st century. But the nature of the data they collected means they approach similar problems in radically different ways.

If Google Now is the street, Facebook Home is the café

Ultimately, it's a clash of styles. Compare Facebook Home to Google Now. Google Now also tries to pull information out of different apps and web services and foreground it on your phone. But Google Now presumes that what users want most is data scoured from official sources: maps, weather information, train schedules, sports scores. Facebook assumes that users want status updates and photos from people close to them. Which of those is more useful or entertaining? Which of those is more valuable to users, advertisers, and the technology platforms that connect them? If Google Now is the street, Facebook Home is the café. Where do you spend more time? Where do you spend more money?

For Facebook, Google is both a problem and an opportunity. For Google, Facebook is mostly just a problem.