Check out the configuration and instructions for more info.
We also made this feature available to early adopters, because I've been wanting to do this since the beginning, and the early adopters should have had it then. :-)
In the coming weeks we plan to improve this feature with new authentication options and attachment support (so you can post pictures from camera phones).
Oh, and props to our new code monkey mahlon for most the work on this new toy.
Update: Many people are asking about the delayed comment notifications over the last few days.
We used to have 2 email servers, even though we only needed 1. Then 1 blew up the other day, and the 1 surviving one wasn't enough to keep up with all the email and got behind.... so now we have 3 mail servers online, but that one burdened one is still catching up, sending out many-day-old mail. You'll continue to get old mail for a while, but it should catch up soon. We're going to be redoing our mail architecture, though, after seeing how easily our existing setup died.