Jake here, and Newsarama has a fascinating review of the Book 3, Volume 4 DVD.

The reviewer comments about Avatar being one of the best series of the decade.  They also say the fight sequence between Ozai and Aang is "one of the best TV animation sequences of this decade."

The article also continues speculation about "more stories" set in the Avatar world.  Again, take this with a grain of salt because there are no plans really to continue with the animated series, or even a spin-off.

Thanks to Nico (The Thriller) for the heads up on this article.

Also, Jeff (Serpent_Guard) found this article: http://www.buddytv.com/articles/avatar-the-last-airbender/avatar-creators-share-thoughts-21908.aspx.  It also is an interesting read, but not much new info is in it.