On Letterman Thursday night, Julia appeared to plug ABC's "Geppetto" (she looked great, by the way). Dave asked her if she was trained as a singer (since Geppetto is a musical), and she told him she was. I suppose to prove her point, she went to center stage and began to sing "Sixteen Going On Seventeen" (not sure if that's the exact name of the tune, but it's from "The Sound of Music"). Midway through the song, Jerry came on stage and sang the other half of the duet with her (Jerry was apparently _not_ trained as a singer). It was a nice moment...they seemed to enjoy it as much as the audience did.
As a side-note, during the interview portion of her segment, Julia said she has a bad memory, which works to her advantage when it comes to watching Seinfeld reruns.She doesn't remember the plotlines, so she can see (and enjoy) them as a first-time viewer would.
Did I mention that she looked great?