Google fan Lookon has created a Bot to post to his Posterous blog, and written detailed instructions on how to do it.
It’s straight forward enough, add the bot and log in to the form it gives you. The next time you add the bot to a wave, the first wavelet gets posted at Posterous and it returns the URL for you to check.
Posterous seems to have the most diverse posting options of any blogging software available, and the addition of posting from waves puts it again at the forefront.
Now the bot needs to monitor comments and return them to the original wave for even tighter integration.
How to write a blog using Google Wave Robot for Posterous [Western Bridge over Google Wave]