Thanks timethief, but I have tried it in Firefox 11, Chrome 18, IE 8 / 9, Safari 5.1.5, Opera 11.62. It doesn't have to do with flash, javascript, my UA, my ISP, my router, etc. Other people experienced it and reported it to me.
Make sure you are logged out of wordpress.com and go to
http://blog.cardinalnewmansociety.org/2012/04/17/archbishop-chaput-on-urgency-to-witness-to-faith
Click the email icon, the page will reload instead of showing the email message box.
If you log back in, or if you use the homepage, it will work correctly. It only happens on the single post pages when you are logged out.
Here is a demo video I made:
http://www.screenr.com/52g8