Re: The Avengers 2! The Official News and Speculation Thread - Upgrade section 5 -
The impression I got from Whedon in the Comic Con interview was that they were going to redesign Ultron somewhat.
Whedon poked fun at Ultron's fixed "screaming" face.
"A bat signal, for listeners who might not know, refers to the children's character The Bat Man - a strong gentleman who fights crime nocturnally."