We’ve heard rumors about it and we’ve seen screenshots, but today, Facebook officially announces replying via email.

Reply via email essentially allows you to reply to email notifications such as comments and wallposts without having to visit Facebook itself.

When you receive an email notification about comments, you can just click “Reply” and start typing a comment at the top of the email. Then hit “Send” from your email and your reply will automatically be added as a comment on Facebook without you having to even log in.

If you aren’t currently receiving email notifications for comments, be sure to check out your Account Settings. From the Notifications tab, you can choose to receive email notifications when people comment on posts and content, as well as for many other common Facebook activities.

One can’t help but wonder how drastic an impact this will have on Facebook’s monthly uniques. With Twitter’s activity largely based offline and many believing it’s the beginning of the end for the service, are we going to see similar drips in traffic growth with Facebook?