Facebook’s e-mail isn’t really e-mail. That is the story, according to CEO Mark Zuckerberg (News - Alert). In fact, as posted in a Business Insider piece, the new messaging system unveiled today is a slightly different version of e-mail.

Andrew Bosworth, director of engineering for Facebook (News - Alert), refers to the new system as IM with e-mail layered in. The three components: seamless messaging; conversation history; and social inbox.

With seamless messaging, you can easily be reached anytime and anywhere, though e-mail, SMS or IM. The conversation history allows all conversations to be in one long stream that can be kept for eternity. The social inbox allows you to filter based on your friends through options such as messages, other and spam.

Another Business Insider report takes these key elements a step further, calling the seamless message the “next evolution of Messages.” This feature allows you to determine how you will talk to specific contacts, based on preferences. The platform will remember those preferences and when you begin to type, will send the messages through that channel.

Every Facebook user who wants an @facebook.com e-mail address can have one. This will allow users to share with friends over e-mail, whether they are logged in to Facebook or not. There are no subject lines, no cc, bcc and you can send a message by hitting the enter key, indicating this is not e-mail.

The conversation history allows the user to organize conversations primarily around people. All messages with a specific person will be kept together in one place – regardless of the channel of exchange. Everything can be viewed as a single conversation.

The social inbox is perhaps the coolest feature of all new Facebook e-mail features – I mean, messaging features. You no longer have to have the e-mail message from your best friend sandwiched between a bill and a bank statement. Messages that are not from sources you designate as friends will be sent to the “Other” folder so you can look at them separately.

This week, expect a number of different announcements from companies like Facebook and Google (News - Alert) as this week marks the start of the Web 2.0 conference in San Francisco. There, these two heavyweights are expected to lock horns in the battle for dominance over the financial opportunities of dominating the Internet.