In 2009, Facebook first gave vanity URLs. Before that your profile was reachable at an address that looked something like http://www.facebook.com/profile.php?id=1234567890. The arrival of vanity URLs allows us to customize it for convenience and simplicity. Mine is http://www.facebook.com/jason.t.viglione. Not everyone has set that.
Since November of 2010, if you have a Facebook account, you have had the ability to have a @Facebook.com email address. They launched this feature on November 15th of that year. It hasn’t been well publicized since then. Now your facebook email will sync with Timeline. That means that you can send me an email at email@example.com. From within Facebook you can send email to any external address as well.
This may not seem like something of importance but it is to Facebook. Approximately 25% of all time spent online is done on a social networking site like Facebook. If you can do everything from within Facebook you have no reason to ever leave. While that may not ever be 100% true, they will get as close as they can. At this point, just about the only thing you can’t easily do from inside Facebook is shop. Most people are on Facebook and use its messaging system simply for internal messages. The ability to send emails to any external domain means you don’t have to open another browser window/tab or email client for the few people that aren’t on it. There is no chance of getting distracted on your way back. Facebook obviously likes keeping you here.
The timing of this is suspect as well. Even though sending emails to/from external email addresses has been enabled for some time, the syncing of Timeline name to email address just simplifies the process and requires no interaction from you. If you have Timeline, you have a @facebook.com email alias. The only social network that has ever posed a threat to Facebook, albeit a small one, was Google+, which is heavily integrated into Google’s own Gmail. By logging in with your Google username/password credentials you have all of Google’s ecosystem in front of you Single Sign-On as an authentication technique is proven to keep your customers using your services longer. Google+ has been around for nearly a year and hasn’t made much of a dent on Facebook’s user base, but it has also just recently gotten a much needed face lift.
This is another step in the current day version of the US vs USSR space race between Facebook and Google (no direct association with either company and either company). Each is vying for your constant, undivided attention. The more they can offer without extra involvement from you makes the user experience easier for you.
If you are a heavy Facebook user, you have probably set your Timeline name by now which means your @facebook.com email is waiting for you.