According to Weekly Young Magazine vol.52, a new TV series of Kiss x Sis
was announced. The staff and the cast are the same as those of the OVA series. The third volume of the OVA will be released on November 20th, bundled with the manga volume 5 Limited Edition.
Source: Scan of Weekly Young Magazine
Updated on Nov 22nd
According to the official website, the fourth volume of the OVA will be released on June 4th, 2010.