There is a rather significant and recent thread on this topic in the NYC forum, too, including reviews of the lounges and access issues (or, really, the lack thereof).
Here are a few of the recent ones:
http://www.flyertalk.com/forum/new-y...k-showers.html
http://www.flyertalk.com/forum/new-y...minal-4-a.html
http://www.flyertalk.com/forum/new-y...ounge-jfk.html