After using Tumblr a bit for FourthSegment, I began realizing that it had many of the features I was ‘missing’ in Posterous, with or without actually realizing it.
Tumblr unfortunately doesn’t have a way to import old content, so I’ll leave it where it is. (Hint: It’s here.) I may toy around with still using Posterous’ autopost and email submission, and I’ve set it up to autopost here. Or use it for some subset of things. We’ll see how long that all lasts.