As announced by Peter Dalgaard for the R Core Team today, R 3.1.1 has been released. Codenamed "Sock it to Me", this is a patch release for R 3.1, and mostly includes minor bug fixes. It also includes some small improvements, including easier access to package help files, improved accuracy when importing data with very large integers, and some clearer warnings and error messages. You can see the complete list of changes in the NEWS file.
You can download the latest source files from your local CRAN mirror (as soon as the updates propagate). As of this writing updated Windows binaries are are already available; MacOS binaries are expected in a few days.
R-announce mailing list: R 3.1.1 is released