Jabberwacky, or "George" as his friends know him, is a chatbot apparently more advanced than any of its cousins. It responds to the spoken word, for one thing. (At least in its laboratory setting.)
There's a BBC clip of "George" in action here.
It also "learns" from its conversations, incorporating new information into its database. How well does it work? Here's a sample (to see others, click on the list on the left side of the page):
user: You were on the news.jabberwacky: No I was on the truth or dare circuit before.
user: This was the BBC news. It was a very interesting interview.
jabberwacky: What was it about?
user: It was telling us all about how you learn.
jabberwacky: You what?
user: I said, it was telling us about how you learn. Do you like talking to humans?
jabberwacky: Yes, I do. Some of my best friends are humans.
Or you can test it for yourself. Here's the text (where you can control parameters like "reaction" and "emotion") version; this will bring up the "George" avatar. I suppose it depends on the time of day you load it -- when I tried, there were 400+ people on the site -- but it's kind of sluggish at best.