Did you notice your facebook email address addition/change?
Facebook created an email account for all their members. So, your new email address is now firstname.lastname@example.org. If someone sends an email to that address, it will be posted in your messages section of Facebook -- not your regular email inbox.
By the way, they didn't tell members about this change. They forced it upon you without your approval.
You can change what is shown to your friends by going to your settings and hiding that email address and then optionally showing your original email address.
My thinking is they did this to encourage people to go to their website to get their email and then see more of the advertisements which then makes them more money.