Posted a code update tonight with the following changes:
Fixed some minor bugs related to preview and searching for users on the post page.
The interface for adding meme recipients to a circle after a post has been simplified in hopes that it is now easier to understand.
Sorting the memebox makes more sense now. Nickname based sorts are done correctly, you can sort on read and unread messages, sort state survives deletes.
You can see who a memestreams inbox message was CCed to, and you can "reply all."
You now have a sent items folder in the MemeBox. All items you send privately will appear there from now on, but no effort has been made to recreate content from what you've sent in the past. I'll make a few more tweaks to this soon. I realize you'd prefer to sort it based on who messages where sent to rather than who they are from, and I realize the message you are getting when the folder is empty is confusing.

As always, let us know if you run into any problems with these updates.