From animesuki forum:
Manga series! (from early sale of Manga Time Kirara Forward, via Twitter)
Mahou Shoujo Madoka☆Magica (manga adaption)
Release in February, March and April by Houbunsha, total of 3 volumes. No serialization.
Mahou Shoujo Orico☆Magica (spinoff manga)
Art: Mura Chloe
Release after the anime is done, presumably Spring 2011. No serialization.
Mahou Shoujo Kazumi☆Magica (spinoff manga)
Art: Tensugi Takashi
To be serialized in Manga Time Kirara Forward starting the next issue.
Mura Chloe posted an illustration of Mami in her website; maybe Orico Magica is some kind of Mami's backstory? Also, last month she mentions her spin-off manga is based on "January anime" that "has a grotesque element in it."
Houbunsha's special Madoka☆Magica site openFull quote, if anyone is interested… (from Twitter)
"I'm working on spinoff manga adaption for January anime. Since I'm also in charge of scenario and few characters, it won't stray to much from my style. The anime series has grotesque element in it, so I wish the adaption would went on smoothly…."
Also, pixiv pages:
Drawing: Taniguchi Junichiro
Featuring long interview with director Shinbo Akiyuki, illustration from Ume-sensei and 39 staff comments; not sure when I will be able to get my hands on it (probably after new year), but I will translate them all… I think.