I just wanted to give a hat-tip to Ben Zittlau for his post on how to configure your Posterous blog on a Dreamhost-hosted domain. His post was just what I needed to configure a subdomain on my web site to act as a custom URL for my Posterous blog. The only difference is that to configure your blog on a subdomain, you will delete the 'fully-hosted' feature for just the specific subdomain--i.e., "subdomain.yourdomain.com" versus just "yourdomain.com".