I recently installed Auto Social Bookmarker from Mass-automation to a few of my Blogs.  It is a bit cumbersome when you order because you are not delivered the plug-in right away; however, i submitted an e-mail and support ticket and both were answered promptly when i woke up in the morning.

This tool looks like it may be the answer to hands off social bookmarking.  Once the plug-in is configured the it will post to the bookmark sites every time a new post is delivered.  It will even  bookmark future posts so you can upload articles, set the distribution date, and the blog will simple manage and promote itself as long as you have content.

 I will post a more detailed review of the product and the result it provides after it has been installed for a while.