With nefarious spam on the rise throughout the blogosphere (both human and inhuman), it looks like Posterous has finally given users the ability to moderate comments upon their blogs.
If you want to prevent comments from appearing on your site without your approval on your Posterous blog — now you can. You’ll get an email whenever a comment gets posted to your blog, and it’ll be up to you whether that comment gets approved or rejected. You can turn this setting on for each of your sites individually.
You can either approve or reject the comment directly on the post, or go to your Manage page and click Moderate now. (Official Posterous Blog)
This move will probably not please many spammers as Posterous was one of the few upcoming platforms that lacked any real defense against spam aside from account registration (which does little to keep spammers at bay).
Posterous has not indicated on whether they will extend comment moderation to their iPhone app (a feature included within the WordPress iPhone app), although for now it looks like Posterous may become less attractive to spammers (especially of the human kind).