I saw a teaser trailer of Shakugan no Shana Second today at the Rondo Robe, which I'm sure will be available on the offcial site soon as well.
Not much to discuss except for the three keywords:
The five seiyuu guests who appeared today (Kugimiya Rie/Shana, Hino Satoshi/Yuuji, Kawasumi Ayako/Kazumi, Nabatame Hitomi/Margery, and Itou Shizuka/Wilhelmina all were excited about doing the second season.