A small but notable development at Facebook means that if you're replying to a comment posted on your profile, you can now do so through regular e-mail.
A post on the Facebook blog explains it: "These notifications--for comments on such content as status updates, photos, videos and Wall posts--allow you to stay informed about your Facebook friends' activities without being logged in when you're on the go, on your phone or at work. Today, we're launching the ability for you to participate in these conversations by replying directly to these e-mail notifications."
So, basically, if someone comments on something you've posted to Facebook, you can respond and add an additional comment by replying to the e-mail notification that alerted you to it in the first place.
Will Facebook make it possible to do more--say, respond to private messages--through basic e-mail? Currently, users have to click the link in an e-mail notification, log into Facebook, and reply through its messaging system. It's something that many members have wanted, but that Facebook hasn't implemented despite making some tweaks to its messaging system last summer.
Don't hold your breath on that one. Keep in mind that Facebook is advertising-supported, and that requiring members to log in to communicate on the social network means they're seeing more ads that they wouldn't be seeing in their e-mail in-boxes. On the flip side, we all know that Facebook isn't just for kids anymore, and many workplaces block access to Facebook and other social networks. Allowing a limited amount of Facebook activity via e-mail could be good for overall levels of that magic Facebook pixie powder, "user engagement."