When you activate the WordPress.com Stats plugin on a self-hosted install, it asks you whether you want to register the site with WordPress.com as well. This makes it show up in the admin bar that appears across the entire network.
I have an identity on the J-School network that’s much more relevant than my WordPress.com identity. I should be able to register my website with the J-School’s multisite instance in a similar fashion, and have my identity within the J-School network reference my self-hosted data (posts, status updates, photos, links and so on).
This would be neat.