This blog is updated daily..
A general description is here.
win.version() and Sys.info() know about recent and upcoming Windows versions, including if they are running on a 64-bit platform.
The listbox used by select.list() now responds to double-clicking an item (as if the item had been selected and then the OK button pressed).
The header iconv.h is now installed, and can be used by packages in conjunction with PKG_LIBS=-liconv .
The value of "default" for the postscript() 'paper' argument for savePlot() and the windows() graphics device menus is now interpreted as "special" (rather than "a4" or "letter"): it can still be overridden by setting ps.options(). (This changes the default output to be most suitable for inclusion in other documents rather than to produce a page for printing.)
The shortcuts created by the installer now start R in the user's personal folder (typically 'My Documents' or 'Documents').
If Rterm is invoked as 'R', the status code (as passed to q()) is now returned (rather than 0 or 1).