The current version of Panoply is 2.6.3, released 2008-10-23.
Panoply requires a computer with a Java 5 runtime environment, or better, installed. If you are using OS X 10.5 (Leopard), or if you are using OS X 10.4 (Tiger) and have been running System Update, then you should have Java 5 on your Mac.
In addition to the map overlays (continent masks and outlines) included in the Panoply application distribution, there are a dozen other overlays available for separate download.
For additional scale colorbar palettes, the cpt-city website includes many CPT format files which are compatible with Panoply.
Installing Panoply should just be a simple matter of double-clicking the PanoplyOSX.zip or Panoply.dmg icon on your desktop. Then drag the PanoplyOSX folder to wherever you prefer to keep applications, probably either your user Applications folder or else the system-wide Applications folder.
The Panoply package for Mac OS X folder holds the following items:
To run Panoply on Mac OS X, just double-click on the Panoply application.
The Panoply package will also notify Mac OS X that it can open files with a .nc filename extention. This means that unless another application has also done so, double-clicking a netCDF file appropriately named with a .nc extension will cause Panoply to launch (if it's not already running) and automatically open the file.