Comment on WordPress Social Network Theme by Mark.
I guess social signals are a factor in SEO. I have tried like you to be a social media guy but it does not work as well as SEO. But if this is a factor in SEO than maybe the Google +1 button might be a consideration for an update. You do not want to clutter your page up with all that junk but if these are the rules of the game than maybe.
I also like Stumbleuopn for traffic.
Also the Facebook like button fb_xd_fragment thing change might not be bad idea, but you know better than I on this.
I think Facebook, Twitter, Stumbleupon and maybe +1 are the big three of social media.
YouTube is actually the largest social site on the web, next to FB, but I do not know how to harness that power. Some people have a YouTube button to their channels others I know basically just market and promote with Youtube.
One more idea, but just an idea. I saw a WP plugin that was a stumble button, but it works like related posts to improve click through. This again might be an SEO factor post Panda.
wordpress.org/extend/plugins/stumble-for-wordpress/ I wonder what your take on a plugin like this if the button was in the right place?