Via Entertainment Weekly:

"I found it funny in The Phantom Menace when Darth Maul got cut in half," Clone Wars supervising director Dave Filoni says. "I thought George was definitively saying to the fans, 'There's no way this character is coming back. This is not a Boba Fett/Sarlacc Pit situation where, because of fan love, Boba gets out of that thing any number of ways.' Fast-forward ten-years, and I'm the one to bring Maul back."

Well, mostly. Filoni acknowledges that the order to resurrect the Sith Lord came from George Lucas himself, who became more interested in his Phantom Menace creation while developing Savage Opress for the last season of The Clone Wars. Awesome as Maul was in the movie, he barely got to do anything before the old chop-chop. When asked if Maul's return is motivated by the feeling that he was underutilized in The Phantom Menace, Filoni says, "I think in part."

Filoni's biggest challenge, though, will come from the legions of fans ready to shout "No way!" at the very idea of a Maul return. But addressing the (un)believability of his survival could make for some interesting drama. "First of all, how does he survive getting cut in half?" says Filoni. "Plus, he fell! And also, don't forget Obi-Wan Kenobi is still around, so I'm sure Maul wouldn't be very happy with him."

Fans will note that there is precedent for this kind of resurrection. "The Dark Side of the Force is the path to many abilities some consider to be…unnatural," Darth Sidious says in Revenge of the Sith. Sidious and his master found a way to use the Force to cheat death—that's how he was able to keep Vader alive after that little swan dive into a lava field. Couldn't Maul have picked up on some of that too? Says Filoni, "He's suffered through a lot to keep himself alive and implemented the training of his master to do so."

Once you get beyond the plausibility issues, what's left is actually an amazing storytelling opportunity. The Clone Wars has featured other characters from the movies, but mostly original trilogy stalwarts like Chewbacca, Tarkin, and Ackbar. Those are all characters whose fates have already been decided. "Here, we're moving forward with Maul," Filoni says. "He's more than ten years older than he was in The Phantom Menace. That's immensely satisfying, because now nobody knows what's going to happen to him. I know, but nobody else does."

Thanks to Robb Hammond for the tip!