Lulu is now saying her sister's name. When she used to say it, it sounded kind of like "Bebe", and Penny used to say, "I'm not Baby", but now it's crystal clear: "Penny", she says, and I have a feeling she's not ever going to stop saying it.
Lulu being Lulu, it's not really spoken, either, it's yelled, with great gusto: "Pen-NEEEE!!". It's screamed when she wants what Penny is holding. It's shouted when she can't see her sister in the same room. This morning she yelled it as soon as she woke up, running to her room as fast as her footy pajamas could take her.
I can feel that this is a turning point for Penny and Lulu. Each day, with new words, Lulu is seen by her big sister as less of a baby and more of a playmate. Penny is still surprised to hear Lulu shout her name, but soon she won't be, I suspect. Soon all of us will forget how new and novel this is.