The commentariat thinks Facebook’s “Gmail killer” arrives on Monday. One rumor has it that Facebook’s email will integrate Microsoft’s Office Web Apps, but it’s hard to get excited about another document editor (consumers don’t use spreadsheets or Powerpoint). Obviously, walled garden email is a non-starter, but how much would it really change the way Facebook thinks of the world? (It already distributes Like buttons and status updates, though of course there’s that ongoing battle over contact info.) Facebook has used its messaging tool for different kinds of alerts, with mixed results. If it squeezes in too many alerts, invitations, calendars – why is there no calendar in Groups? – Skype, chat, IM, etc., how could Facebook make an inbox less overwhelming for consumers? Would access to your social graph make auto-prioritization more powerful than Google’s? Perhaps we’ll see.