ArcGIS 10.3.1 is the current version of ArcGIS. It is available for installation via the same process as previous versions.
The process to install or update ArcGIS is somewhat more simple than in previous versions. It is documented on The Spatial Initiative’s website at http://spatial.usask.ca/software/install.php. It is important to note that the name of the Windows share for the install files has changed to \\gisjane\Install_Desktop1031.
ArcGIS uses Python 2.7.8 for scripting, including internal scripts.