New DeepScreen technology allows avast! to make more intelligent decisions about new/unknown files. DeepScreen is a successor of AutoSandbox, now upgraded with some additional new technologies such as dynamic binary translation and dyna-gen announced earlier.

http://forum.avast.com/index.php?topic=132502.0

Its in v9 beta: http://forum.avast.com/index.php?topic=134419.0