I would say yes. Look at this videos, very brutal KOs. Against Herol Graham: http://www.youtube.com/watch?v=OhVi7cH-LaQ&mode=related&search= Against Terry Norris: http://www.youtube.com/watch?v=M_Id6-oOY1U&mode=related&search=
Barbados Joe Walcott makes Jackson's punching power look like a toddler. Ask any historian. http://coxscorner.tripod.com/walcott.html
the dude was a lightweight who knocked out heavyweights. He's considered by most historians as one of the greatest punches of all time. The man was a beast.
Jackson's ko of Norris is identical to the sleep job Pavlik put on Zertuche. It was identical. P.S. Not implying Pavlik is p4p though.
Jackson had some great KO's but he's not P4P the best puncher, not by a mile. The ring did a top-100 punchers of all-time a few years back and i promise, guarantee, he's not top-75 if he even made the list.