According to MSNBC, through a Newsweek editor, the Kurds may have had a hand in the capture. The editor felt that a Kurdish capture was unlikely, but that the 300 lb. bodyguard probably reported Saddam's location several times, and US forces caught up with him on the fourth or fifth try. At least this is a mainstream mention of the possibility of a Kurdish capture, although it was quickly dismissed by the talking heads.
More interestingly, the interview revealed what probably did happen at the moment of capture. The hollywood story of Major Gentle Ben meets a meek Saddam is, not surprisingly, bunk. Sources indicated that Saddam was much more defiant, spat on the soldiers, and recieved a blow from either a fist or a gun butt before submitting.