Facebook as per an announcement made on April 12, 2012 will now use email address that will be linked to Timeline. Basically your name used for Timeline on Facebook, now will be same for the Facebook email account. For eg. if your name on Facebook Timeline is www.facebook.com/thegeeksolutions then your email address on Facebook will be firstname.lastname@example.org. You can use any of the email services like gmail, hotmail, yahoo, aol etc to send a message directly to the a Facebook Timeline Profile. Facebook also announced that they will be rolling out this features over the next few weeks moreover if you have already selected an email address then it will remain unaffected.
You can even check whether you have selected an email address earlier, if not you can also set an username for the same HERE