You’ve built an enormous business around a desktop website. Unfortunately, people around the world are spending more and more time on mobile devices. The vast majority of these devices run software from only two companies. One of these companies is actively competing with you.

You cannot put your future in a competitor’s hands. So what do you do? Do you enter uncharted territory, make your own mobile operating system, and hope people switch?

Of course not. You make your competitor’s system yours — overnight. Facebook Home is a trojan horse designed to steal the Android experience, and the Android user base, right out of Google’s hands. The majority of speculation over the last year or two had been that Facebook was working on its own mobile OS. It may well be, but this move is so much smarter on a number of fronts:

  1. Time. Home significantly increases Facebook’s mobile presence without being everything. A lot of time and care seems to have gone into it, but it’s surely far less than a full-blown operating system would require.
  2. Installed base. Built in. The sales pitch is very simple: If you have a device that Home supports, download it. No money, no switcher headaches. Blackberry and Windows Phone sales prove that people aren’t looking for new platforms right now.
  3. Software Experience. Facebook’s engineers have surely learned a lot from this project. That experience will be reapplied not only to expanding Home itself, but to building a full-blown OS if they want.
  4. Hardware Experience. While the software is the real news here, Facebook took the initiative to also start working with a handset maker. The HTC First is hardly a “Facebook phone”, but it’s a chance for Facebook to experience the complexity of coordinating hardware, software, and carrier partnerships from a distance. Remember the Motorola ROKR? Remember what happened fifteen months later?

Facebook has loudly and confidently entered an arena it has no prior experience in, and has set a clear path to expand its influence at its own pace. Facebook Home will provide a halo effect to current Android users that warms them up to a full-blown “Facebook phone” in the years to come. It gives Facebook the experience, confidence, credibility, momentum, and time to build a better and broader mobile experience than they would have been able to build otherwise. It’s as prudent as it is ambitious.

I think we’ll know well before the end of this year how Facebook Home affects handset sales. If buyers start asking “does it have Facebook Home?” — and I think many will — that will be bad news for both Google and Apple. However, the Google – Facebook war is sure to be more vicious than the Google – Apple war because Google and Facebook have the same customers: advertisers. Users are their currency, and Facebook is about to rob the bank.