J.C.Staff just announced in the July issue of ASCII Media Works' Dengeki Bunko Magazine that the third and final season of one of their heavyweight adaptations, Shakugan no Shana, will begin airing in 2011's Fall season.
Interestingly, having stuck true to the light novels for both the first and second seasons, J.C.Staff is opting for an anime-original ending this time and making this their final adaptation even though the light novels are still ongoing. Sales of SnS II were strong, and the light novel is very popular in Japan. It's strange they are not milking this cow any longer. Maybe it's because they have Index now? (To be honest, Index is definitely a far superior series)
Via.
Magazine Scan