According to Anime Newtype Channel, Sora no Otoshimono
was announced to be 14 episodes long. However, one of the episodes won't be aired on TV since the episode is too "dangerous".
Source: Anime Newtype Channel
The PR posters of Sora no Otoshimono were displayed at a railway station next to Comiket 76 site last month. They were censored by the railway office and the breasts and the underwear were masked.
Masked posters of Soraoto
Updated on Sep 21st
The episode will be released on the volume 7 of the DVD.
Source: Web Newtype