Yeah, the guys from Posterous have done it again.
Now you can have private posts in your Posterous by just sending to private@posterous.com. Only people who have the unique URL (and yourself of course) will be able to access it. Pretty nifty.
On a smaller note I see that the "Manage" area has been adjusted a little, you can now see #comments and #favs for your posts. Neat.
Time for some fan wear so we can spread the love :-)