The final installment of the R 2.x series is now available: R 2.15.3 was released this morning. If you build R yourself, the source files can be downloaded from CRAN now; pre-built binaries for Windows, Mac and Linux will be available from the various CRAN mirrors over the next few days. This update mainly fixes a few minor bugs, and is a drop-in replacement for R 2.15.2.
As announced in January, the next version of R will be R 3.0.0 and will be released in April. No major changes to the language are planned, but internally R will support larger objects to better make use of platforms with large amounts of RAM. This isn't likely to affect R users, but package authors (especially for packages using C code) should test their packages against the development version of R 3.0.0 now to avoid any surprises.
R-announce mailing list: R 2.15.3 is released