The Tales of Symphonia: the Animation Official Site has been updated today with a new trailer for the upcoming Tethe'alla Arc. You can see it automatically playing on the upper left hand corner once you visit. Though for some reason, the new trailer doesn't have any audio in it.Anyway, the trailer mostly starts off by showing scenes of the Sylvarant Arc, and is then followed by scenes of the upcoming new arc. The lack of audio should hopefully be fixed soon.
Also from the site, the first episode of the Tethe'alla Arc will be having an advanced screening in some Japanese theaters from December 12-18, 2009. It will be showing in the Ikeburo Theater Dia (Tokyo) and Umeda Theater (Osaka) on those dates. More information on this will be released in time.
The actual release of the Tethe'alla Arc DVDs will be on Spring 2010. To those interested, the Tethe'alla Arc's opening theme "Tenkuu no Canaria" by Nana Mizuki has already been leaked on YouTube.
EDIT:The trailer with Audio can be found here (thanks to cutepresea for the link!). Due to having copyright problems on YouTube with Frontier Works in the past (YouTube deleted some of my close friends' accounts just for having the Sylvarant Arc trailers in theirs in the past, and if you'll notice, our chan doesn't have any of the Sylvarant Arc trailers), we won't be putting up the new trailer in our YouTube channel. We'll just put it up for download/site streaming in the future. We don't want YouTube deleting AC's account. That said, I might delete the first Tethe'alla Arc trailer in the future from AC's account as well.