Go to your site stats page and click “Totals, Followers & Shares”
Click the Blog link under the number and the Site Stats » My Followers page will open. Click the Email Followers link.
http://wordpress.com/#!/my-stats/
http://wordpress.com/#!/my-stats/?blog_subscribers
http://wordpress.com/#!/my-stats/?blog_subscribers&type=email

The subscriber stats on your site stats page show you all the users that have active email subscriptions to your blog using the built-in email notification system on WordPress.com. They don’t include users that subscribed using a third-party subscription service or using RSS.

P.S. You cannot obtain any information that personally identifies any of your followers. This is a privacy issue. What's required for registering here is an email address only and that email address for many of us bloggers is a throwaway email address.