Posterous has been acquired by Twitter. Reading their FAQ it becomes apparent the developers plan to spend their future working on Twitter, and not Posterous.

Given its uncertain future, now would be a good time to begin planning your move away from Posterous, to another blogging platform like WordPress or Tumblr. Unfortunately, Posterous has never taken strides to make moving easy.

Can I export my Space’s to WordPress, Tumblr, Blogger, or another service?
Over the coming weeks we’ll provide you with specific instructions for exporting your content to other services.

What are your current options?

1. Wait for Posterous to provide export tools, in “the coming weeks”. This will likely be the most painless method, and retain the most compatibility.

2. Wait for the WordPress Posterous Importer plugin to be updated. It doesn’t work with the current version of WordPress, but odds are they’ll be under a lot of pressure to get it updated soon.

3. Move today, using a bit of a messy workaround.

• Temporarily register a private WordPress.com blog
• Go to Tools ? Import and Select Posterous
• After import has completed, go to Tools ? Export and select WordPress eXtended RSS (WXR) file for all posts and comments.
• You can then import this file to a self-hosted blog using Tools ? Import.
• At this point you could perform another import from WordPress to Tumblr.
• Switch your DNS A record from the Posterous IP to your new self-hosted server, or Tumblr.

This method uses the WordPress.com importer, as it seems to be the only one currently functional. However, there is some more work left to do. Re-upload or re-link all your post images as they’ll be pointing to wordpress.com. You may lose any posts marked as private. You’ll need to update the permalink structure or your WordPress blog to retain internal links, and links from search engines. Your RSS feed will be broken.

As you can see there are a number of hurdles to overcome migrating away from Posterous immediately. Self-hosted WordPress blogs offer much more flexibility, but require a web hosting account, and vigilant updating to prevent security issues. A migration to Tumblr would probably be the best move for most people, but currently requires two imports. If you have the patience and faith they’ll follow through with their promise, we suggest you wait for Posterous to release their exporting tools.