I've moved this blog now to Posthaven. I was one of the cofounders of Posterous and was the main designer and wrote many of the major features you liked about this software.
You should move your blogs too. I wrote up a comprehensive guide to all of your options for moving away from Posterous, and you can read it here: The Posterous Migration Guide -- I review all the options including Wordpress, Tumblr, Squarespace, and Edublogs.
Posthaven is $5 a month, and we're rebuilding post by email, the contributor system, the email notification system, the bookmarklet, and everything else you liked. I hope you'll take my personal invitation to join Posthaven.
https://posthaven.com
