This blog is updated daily..
A general description is here.
Help in base and recommended packages is no longer zipped: it makes little difference for parsed Rdtext, latex and examples files, and prebuilt latex and examples files will be removed shortlyre now built when needed.
Options --use-zip and --use-zip-help in R CMD INSTALL are no longer available and --auto-zip only zips data (or not).
file.access() proved unreliable on some network-mounted file systems (probably a Samba issue), so it has been replaced in R CMD INSTALL by a directory creation test. (Reported by Simon Urbanek and Ruth Ripley.)