Less than one hour ago, a member of the Pixar publicity team was finally able to officially confirm for me that BURN-E will indeed be the extra short film included on the WALL-E DVD/Blu-ray (in stores this November). The person informed me that a "consumer announcement" regarding the short (and presumably the WALL-E DVD) "should be coming out shortly".
Of course, BURN-E has been all but confirmed before this. Since the title was leaked late last month, we've learned that BURN-E is the welder robot who gets locked out of the Axiom in WALL-E. Thus, the short will likely feature him trying to find his way back in.