Ausiello asked Bill Prady the question that we've all been dying to know. What he found out about Penny's last name:
Question: If you run into the Big Bang Theory gang at the Golden Globes, please ask them if they’re ever going to divulge Penny’s last name. - Jason
Ausiello: As a matter of fact, I did run into them. And I did ask. But you may not love the answer(s) I got. After all, executive producer Bill Prady pointed out, “We were just renewed for three seasons,” so they are in no rush. “We may wait to answer that for a little while.” Golden Globe champ Jim Parsons offered up his own ideas, however unlikely. “I thought Penny Moonves, as a tribute to the man up top,” he suggested. “[Or] sometimes the prop master’s last name appears on things, which would be London. But I don’t think they’re going to go with that.” Yeah, I didn’t think so, either.
So not great news. :( Although I guess its a positive that they intend to answer it at some point.