I see old messages on various obsd related lists about ksh93 having been at least considered for a package and it not clear if it every was a package, but at any rate does not appear to be now.
I wondered if there is development on that or maybe unofficial packages or something. The reason I ask is that I'm unable to get it built from the proceedure and tool available at: http://www.research.att.com/sw/download/ I'm not sure if the site is out of date or what but following carefully the proceedures shown there ends with packages not being found or an unusable ksh93. I've built it before from that site so am guessing it has grown out of date or become neglected.