Update on my situation: took the phone to Sprint repair tech - tested battery = OK - factory reset phone - no change (BATTERY: continual rapid depletion - 50% after 2 hrs, 18 mins and phone has been doing nothing, just sitting in pocket with screen off .. ANTENNA: still no connection to network, but wifi worked) - paid $35 fee to have phone replaced (I'll receive new phone in a couple days.) I'll post performance of replacement phone for a few days before I add any apps and then stats for a few days after.
Personally I believe there was a run of a certain component (chip?) in the Nexus S phones that are experiencing the rapid battery drain problem with ICS. It could probably be tracked by #s, but whether someone is doing so, and if they are, whether they are sharing the information from the corp level is doubtful. I have zero proof, just seems likely candidate.
FYI, this Sprint tech had not heard of this ICS rapid battery drain on the Nexus S prior to my visit.