There's absolutely no indication on Posterous that bots are likely responsible for thousands of the page views shown (which given the long tail nature of Posterous I imagine we're talking about the majority of the page views here for a lot of users).
One user even reported that GA was showing 14 visitors while Posterous was showing 9316:
http://adamriggins.com/posterous-post-views-and-google-analy...
Whenever Posterous has given a response the focus has been on disabled javascript, etc. rather than the fact most of these views are likely generated by bots. For example the email you sent to the user here:
http://www.creativenotice.com/how-posterous-stats-work
Given the values are essentially meaningless why show them to your users at all ?