Facebook earlier today rolled out a new feature that allows you to send messages to not just your friends within Facebook, but to any email address. While not terribly useful for power email users, for the casual emailer, this is yet another step towards making Facebook the Inner-Internet.

Pictures, movies, your favorite Internet apps, and now email – pretty soon if you don’t want to, you basically will only need to visit one site on the Internet to do everything – Facebook. As they write themselves:

As we continue to make Facebook more useful for everyone, these changes mean that there’s no need to switch between Facebook and email for your daily communication needs.

It’s starting to remind me a bit of AOL back in the dial-up days, but far more intuitive and useful – and most importantly, free.

While somewhat subtle, I see this email integration as a pretty big deal. First of all it solves the very annoying problem of wanting to share anything you have within Facebook with someone who doesn’t use Facebook. Secondly, the message that is sent out to the email address serves as basically a free advertisement for Facebook – if that person wants to respond, they must follow the link and type something into the response area within Facebook.

The genius here is that the recipient can do this without having to sign up for a Facebook account – basically Facebook is letting their awesome creation speak for itself and I’m sure they plan on having quite a few people who respond to these emails sign up for an account eventually so they can further explore the site (for example you do need an account to write on someones Wall).

I’m sure we can expect an integrated Facebook IM service at some point in the near future as well.