A couple of days have gone bye, since news of an
Arata Kangatari anime adaptation cropped up on the French website
Manga-News, but still no valid source is provided for their story (nor have I seen this on any of the usual English-language sources). So, for now, let's just take this as a perfectly plausible rumor: the manga series otherwise known as Arata: The Legend, they say, will be receiving an anime adaptation in 2011.

The original manga is written and illustrated by Yuu Watase, a rather prolific female mangaka, who so far has had two other franchises adapted into anime: Ayashi no Ceres (Ceres, Celestial Legend) and Fushigi Yuugi (The Mysterious Play). The story of Arata Kangatari alternates between two worlds, with two boys - both named Arata - switching places among them. They are both on the run, but for very different reasons: the fantasy-world Arata is chased by assassins, while the real-world Arata is simply fleeing from a horrible school life.
The Arata Kangatari manga has been serialized in the Weekly Shonen Sunday magazine since 2008 and is still ongoing, with 7 compiled volumes released since January 2009. The 8th volume is set for a September 17, 2010 release in Japan.