According to Weekly Young Magazine No.29, the fourth season of Minami-ke
was announced to be aired this winter (i.e. from January 2013). A new OVA will also be released on October 5th. The OVA will be bundled with the tenth volume of the original manga.
Director: Kawaguchi Keiichirou
Series Composition: Kohno Takamitsu
Character Design: Suzuki Go (General animation director of "Papa no Iukoto wo Kikinasai!
Production Studio: feel.
Sources: Scan of Young Magazine
, Scan 2
, MyNavi News
Update Sep 29
According to Monthly Young Magazine, the title of the fourth season was announced to be "Minami-ke Tadaima".
Minami-ke anime official website
(new key visual)
Source: Scan of Young Magazine