You can now email username@fb.com and it will go to the user's primary email address.
[Edit] See below for full message headers, pretty thin
From: klochner@xxxx.com
Subject: test
Date: November 13, 2010 11:12:15 AM PST
To: klochner@fb.com
Return-Path: <klochner@xxxx.com>
Received: from [192.168.1.104](c-24-6-xx-xx.hsd1.ca.comcast.net [24.6.xxx.xx])
by mx.google.com with ESMTPS id q18sm1677850ybk.3.2010.11.13.11.12.17 (version=TLSv1/SSLv3 cipher=RC4-MD5); Sat, 13 Nov 2010 11:12:18 -0800 (PST)
Message-Id: <509377EA-B8D1-4B06-84A1-8F7CFCE5E89A@xxxx.com>
