The Morgan Library just opened an exhibition of their "latest" acquisitions (since 2004). Impressive stuff: definitely worth a visit, if you get a chance. The exhibition is open until October. Too bad they won't let visitors take photographs: they are the only major museum that has such restrictive rules.
We thought the most impressive works were some photographs by Irving Penn and Diane Arbus. There were some fantastic portraits of Pablo Picasso, Georgia O'Keefe, and T.S. Eliot.