This blog is updated daily..
A general description is here.
predict.loess() now works when loess() was fitted with transformed explanatory variables, e.g, loess(y ~ log(x) + log(z)).
Graphics devices can say if they can rotate text well (e.g. postscript() and PDFpdf() can) and if so the device's native text becomes the default for contour labels rather than using Hershey fonts.
A new header 'R_ext/Visibility' contains some definitions for controlling the visibility of entry points, and how to control visibility is now documented in 'Writing R Extensions'.