There are lineart sketches of two cats (Nyamusasu and Tama) in different online magazines:
1 2 3.
ETA: Two sketches of the main character (Junpei Kousaka) were posted in the same places:
1 2 3.
ETA: The staff (see post from NeoSam below) and two sketches of Mizuno Kaede were posted in the same magazines:
1 2 3.
ETA: The (probably) last update contains two sketches of Kanako Sumiyoshi. The anime will start airing in September 2009.
1 2 3.