This blog is updated daily..
A general description is here.
There is a new component, 'Test files', which if selected will install the package-specific tests. [At a later date there will be support to run these.]
dir() does a better job when dir is of rhe form "d:", the currrent directory is not the root on that drive, and either 'full' or 'recursive' is true.
Sys.setenv() and Sys.getenv() now use the Windows API functions rather than the buggy C runtime functions, allowing longer settings, e.g. for a long PATH.