Facebook is seeking to replace e-mail with what it calls a "modern messaging system" that combines all the ways people send messages – including e-mail, IM and SMS – into a single interface. It's a clear assault on Google and and its popular "social" application – Gmail.

The new system, Facebook Messages, was announced Monday. It allows you to simply click on a friend's face, type a message and hit Enter. Facebook handles the rest. And it comes with an optional "facebook.com" e-mail address.

But a new e-mail address isn't the point. Rather it is the unification of a variety of means of communication. Instead of grouping conversations by threads or organizing them chronologically, Facebook's message system sorts all messages between two people into a single, long thread. That means you see every message sent through the system to a friend or boyfriend in a giant stream every time you open a new message.

As for inbox filtering, Facebook will show messages from a user's Facebook friends on the main page, while messages from people not in your social network are shuffled into another mailbox. The system will get smarter over time, so that even people you aren't friends with on Facebook, but communicate often with, will show up in the stream.

While the system may not convince hard-core e-mail users to switch their messaging life into Facebook, the always-on, centralized system could prove to be highly popular with Facebook's core crowd of youngsters. It also ties Facebook users even closer to the Facebook system, so that the site becomes even more central to how they communicate, plan and cultivate friendships.

The system launches Monday with an accompanying iPhone app.

Mark Zuckerberg announced the product in San Francisco, saying e-mail is just too complicated, and teens were using systems that were much easier.

"E-mail is too formal," Zuckerberg said. "Think of the friction of trying to think of the e-mail address and think of a subject line, write 'Hey Mom,' at the top and 'Love, Mark' at the bottom."

In Facebook's system, messaging gets simpler. You simply write the message and Facebook routes it to the IM, SMS or e-mail inbox without you having to figure out which one to use. The system ties into existing e-mail and IM services, and continues to send out messages to those services.

But the unified inbox lives in Facebook.com and inside its mobile apps.

"We think we should take features away from messaging," Zuckerberg said. "It should be minimal."

The new system includes the ability to include attachments and forward messages.

Facebook's algorithms will decide whether to deliver a message to SMS, IM or e-mail. In order for Facebook to do that, however, you will have to tell Facebook what those addresses are.

"We are trying to make it so that people don't have to think about this stuff," Zuckerberg said. "We are trying to make sure a message doesn't go to five different channels."

Photo: Facebook CEO Mark Zuckerberg announcing its new messaging system in San Francisco on November 15, 2010. Credit: Jon Snyder/Wired.com

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