Without question, this is the money shot from MESSENGER's second flyby. I think this image provides an answer to all of those people who suggested that seeing Mercury again -- even if it was from a new perspective -- might be dull because it would be more of the same. To be sure, this shot of Mercury contains many of the same elements that were visible in the views from MESSENGER's first flyby -- but what a difference a few fresh impact craters make!
Along with that photo they also released a nice view of the inbound crescent, and three detailed shots. Two of those detailed shots -- this one and this one -- show terrain near the equator on the outbound part of the flyby, and are notable mostly because they represent just a small part of a data set that included multispectral imaging AND high-resolution imaging AND spectroscopy AND altimetry, making that area probably the best-studied part of Mercury to date (or it will be, as soon as the science team has time to wrap their heads around that data set).
My favorite of the detailed views released to date was this one, shot across the limb as MESSENGER came in for the flyby:
To help in piecing together where the image releases go, here's a context map I've put together showing the locations of recent image releases, as well as names of craters previously seen by Mariner 10. There are other named craters in between the ones with white letters and Kuiper, but they are hard to spot on the MESSENGER image and I wasn't confident enough in their locations to mark them on the map.