Sega of America filed a new patent on April 2nd 2007 with The United States Patent and Trademark Office for a Sonic Rush Adventure title. This has lead to speculation by gwn that a Sonic Rush sequel is coming.
Released back in November 15, 2005. With the success of the fast 2.5D action platformer Sonic Rush on DS, a sequel is no surprise. However, the new name brings up flashbacks of the badly received Sonic Adventure Dreamcast series.
See how Sonic returned to his 2D roots in the DS original: