Jake here, and its been a while since the last update (exactly 3 months as you can see).  But here is a small tidbit for you.  Matt Hubbard, who was brought on to Avatar to write the "Imprisoned" episode, the sixth episode of Book 1: Water, won an Emmy for Best Writing for an episode of the hit NBC comedy series "30 Rock."  All the details are at this link, so check it out.  The irony here is Hubbard wrote a little bit more of a serious episode, though 106 did have it's humor ("Earthbending style" scene comes to mind), anaaaaaaaaad Hubbard seems to be a bit of a jokester.

It doesn't appear as though Hubbard did any other work on Avatar.  However, it's good to see some Avatar alumni having success well after they left the show.