The R Core Team announced yesterday that the latest update to R, R 3.2.0 (codename: "Full of Ingredients") is now available. As of this writing the source bundle is available for download, but Mac and Windows binaries aren't yet available. You should be able to download them from your local CRAN mirror in the next day or so.
This is the annual major update to R, but looking at the NEWS file, there are no huge user-facing changes that will affect the way you use R. In fact, many of the changes this time round have happened behind the scenes to improve R's engine for performance and reliability. (In particular, this release includes a number of fixes proposed by Radford Neal, bringing some of the performance improvements of pqR to R while maintaining backwards compatibility.) There's also been more progress in handling big in-memory data objects (for example, you can now cbind/rbind matrices with more than 2 billion elements).
There have also been some significant updates to R's byte compiler:
The byte-code compiler and interpreter include new instructions that allow many scalar subsetting and assignment and scalar arithmetic operations to be handled more efficiently. This can result in significant performance improvements in scalar numerical code.
It will be interesting to see benchmarks of R compiled code compared to the 3.1.3 release. Finally, in a welcome update for R package authors, the package-checking system now does a more thorough job of making sure contributed packages comply with CRAN policies.
r-announce mailing list: R 3.2.0 is released