I am looking for a Christmas present for my husband. He works in the field of artificial intelligence. I have seen several robotics kits, but I am unsure which is best for someone who is older (26) and has a lot of programming experience, but not much experience with robotics hardware.

check here you should find what you are looking for they are cheap you can get them from radio shack………..
http://www.radioshack.com/family/index.jsp?categoryId=2032404&cp=2032062.2032398&cid=
Rent a liberal for a day they seem to make great robots…..
get the lego robot kit at toys’ r’ us