They've started posting the interview for Lagann-hen! Some things I found interesting...
-Oh wow. When brainstorming ideas for what to do with Lagann-hen's climax (so it would live up to Gurren-hen's climax), for a while they were actually considering going down a more serious sci-fi route by causing the Spiral Nemesis. :O [I find myself imagining something akin to End of Evangelion. Do not want!]
-Imaishi admits that he wished they could've depicted the Gurren-dan members' deaths in the TV series better. They just didn't have enough time for it. (Ultimately, that's one of the reasons why they all survive in Lagann-hen: because there isn't enough time in a 2-hour movie to do it properly.) Also, they hadn't planned out who would live or die from the beginning, just killing characters when it became necessary in the story (it's natural for there to be casualties in such a huge battle), so they hadn't done enough to prepare for the deaths. They wanted to get across the fact that those guys were happy to go out in a final bang rather than lingering on pointlessly for the rest of their lives, but it didn't seem to work very well. [Well, I thought it was pretty clear.]
-I found this pretty interesting in regards to the timeskip montage: "In order to build up to Simon feeling down in prison later, I wanted to fully show him in high spirits as he's set up as a king. Even if he didn't want to become the top, he did out of necessity, and gradually even he doesn't know what he wants anymore. While in episode 17 of the TV series, it started out with a washed-out feeling since the story begins after he's already in that position." [Now "Viva La Vida" really does seem appropriate.]
-At first, they were planning on starting the movie at Korehana Island from Yoko's POV, completely skipping episode 15. But since the movie would focus on Simon & Nia and they'd already done a lot with Yoko in Gurren-hen, they decided to have her take a back seat this time.