I think there is a Prolog interpreter in the Jun package for VisualWorks.
SmallBrain is a neural net simulator in the Smalltalk archive at UIUC.

Note that Tektronix originally sold Smalltalk on their "AI workstation",
that "Applied Reasoning" started life as an AI company (the founders
learned Smalltalk on a robotics project at Purdue) and I wouldn't be
surprised if "Knowledge Systems Corporation" didn't, as well.  I am not
an AI expert, but I think Smalltalk would do well at it.

-Ralph