I immediately flipped it open and scanned through the chapter on baby names. The reference to the twins "Lemonjello" and "Orangejello" is gone! Unfortunately, they left in the mention of a girl named Shithead (pronounced, supposedly, shuh-TEED), but at least had the decency to put in footnote directing readers to the end notes, where they admit that the source was an anonymous caller on a radio call-in show and that the caller could have been misinformed.
The authors mention on the Freakonomics Blog that, among other things, the new edition corrects some mistakes. I was glad to see that they removed Lemonjello and Orangejello. I have no idea if the message I sent the authors about it had any influence over their decision, but either way I feel vindicated.