Quoted from randomc's episode 6 writeup:

[Mizushima and Aikawa] have already proved themselves adept at translating unusual source material to anime by the brilliant job they did with Oh! Edo Rocket, which was adapted from a stage play by Nakashima Kazuki (who also wrote Gurren Lagann) [...]

I generally barely notice exactly who the creative staff behind anime works are, but this is a set of connections that genuinely startles and impresses me.

(One interesting note is that according to ANN Mizushima also directed Hanamaru Kindergarten, which had a startlingly interesting set of ending animations that are well worth tracking down on their own; each one did its own little mini-story in various genres, complete in a minute and thirty seconds or so. I didn't watch HK itself, but I quite enjoyed the ending segments. I believe you can find them on Youtube.)

For future reference, ANN entries for Mizushima, Aikawa, and Nakashima.

(In another interesting thing, Nakashima not only wrote the original stage play of Oh! Edo Rocket, but he also wrote the script for one episode. I wonder how odd it felt to be scripting his own work as filtered through someone else, since Aikawa was 'series composition' for OER.)