The newest Wordpress plugin from BackType brings web activity back to your blog. It scans sources like Twitter, Digg, FriendFeed, Reddit and other blogs, and brings conversations regarding your posts back to your blog as comments.
That's a good idea, but it will never work as good as it should. For one reason, there will always be services that BackType doesn't understand well or don't know of. Or short URLs that can't be scanned easily for domain names.
I consider my blog to be the one place on the web I truly own. It's my on line home. My on line identity is not my email, it's my blog. I would like every single web service to ping back to it, whenever (I'm) it is mentioned. Twitter, Digg, Flickr, Friendfeed, they should all ping back my URLs.
One more thing: wordpress should accept pingbacks/trackbacks for the homepage, so if vrypan.net/log/ is mentioned somewhere, the service should be able to pingback this page.