In 1999, Steve jobs toyed with the idea of launching a free, ad-supported version of the Mac operating system, and in 2008 he filed a patent on a version of the idea. Microsoft considered making an ad-supported version of Windows in both 2004 and 2005. Neither company tried that tactic, but the idea of pushing ads in return for an operating system is soon to get a real try out, in Facebook’s new app for Android phones, Home.

Home is technically a shell for the Android operating system, not a full OS in its own right (some people think that’s the next step for Facebook). But to the casual user of a phone with Home installed they’d be hard-pressed to tell the difference. Home handles all of a device’s main functions – calls, texts, camera, and more – and escaping it takes determined effort. Facebook say that ads will at some point begin to appear mixed into the “cover feed,” a parade of Facebook updates that takes over the screen of a device with Home installed when it’s idle. It’s like a screensaver that’s a slideshow mixing photos and emails from your friends with ads based on what’s in those photos and e-mails.

Facebook’s take on the ad-supported OS is something of a test for how its users think of their mobile devices. I suspect most people would find the idea of ads appearing as part of the operating system, or screensaver, of their laptop or desktop computer unacceptable. But Facebook’s move makes more sense for mobile devices. Many popular functions of phones are versions of Web sites, which have long been ad supported, and many mobile apps feature ads. That doesn’t mean that there won’t be some complaints when ads start to appear in Facebook Home, but it seems more likely that the reception will prove that the time has finally come for the idea that Steve Jobs and Microsoft decided not to try.