Mike, I am no lawyer but the DEC website points out clearly that "posted" or "no trespassing" property signs must have the name of the land owner on the sign. Of course that helps no one if the sign has been torn down. (BTW, the land is still "posted" for one year from the date of the original posting, even in the absence of the sign.) The website does recommend however, that in the absence of a sign or in seeking permission, one should start knocking on doors seeking out owners.
In the case of climbing along the Nears or any of the other posted areas, one might mention to the home owner that on the advice of their advocate you are seeking them out to discern which properties are posted and/or to ask permission to climb. It would be best I'm sure, if everyone did just that, as Kent has repeatedly suggested these past seasons.
General guidelines for posting of property can be found here among general hunting and fishing guidelines: http://www.dec.ny.gov/regulations/2442.html