At the end of the eleventh volume of the novel, Ore no Imouto ga Konnani Kawaii Wake ga Nai
novel was announced to be concluded in the next volume. The twelfth volume is expected to be released in the Spring of 2013.
Cover art of OreImo vol.11
The airing schedule for the second TV series Ore no Imouto ga Konnani Kawaii Wake ga Nai.
has not been announced yet.
Source: Scan of the 11th volume
(spoiler if you can read Japanese.