(I found this via
Whedonesque.)
Joss performed "Heart, Broken" for
"This American Life - Live!", and the radio episode is now available in podcast form.
Ira Glass's introduction of Joss and "Dr. Horrible's Sing-Along Blog" begins at 28:50, and Joss sings at 34:20. For those of us who like singing along, please note the second half of the song is different, seeing as it needed to not include Zack, Maurissa, and Jed.
(You can also download the whole thing, but I don't know how long that will be available to do.)
PS Am I the only one who gets teary-eyed at that song? It makes me think Joss is mad at us & that we make him sad. :/