The last two icons are new. When you click

of any post a new window will open that allows you to submit the thread to
www.digg.com. If you are the initial clicker, then you need to open a free account with digg and you need to provide a summary of the article before posting to digg. The title, url, and category fields will be pre-populated and you should not alter these. Subsequent clickers will increment the digg count of the post and make it more likely to be seen by others. Please submit only quality threads to digg, otherwise, it reflects poorly on the website.
When you click

of any post a new window will open that allows you to submit the thread to del.icio.us. This is similar to how digg works with the url and description fields being pre-populated. You just add your own notes and tags. I haven't used this website much yet, but it seems like it could be a good tool.
Regards,
--Robert