This blog is updated daily.
A general description is here.
nchar() now gives the number of characters and their width as would be printed in Rgui for non-representable UTF-8 strings, not as they would be printed in Rterm (via <U+xxxx> escapes).
memory.size() no longer wraps around allocations greater than 2Gb. (PR#11596)
Quartz is now trying harder to find the proper font for a given family which resolves font issues on Mac OS X 10.4. Full font names and PostScript names can be used interchangeably. (Note, however that italic/oblique font faces of Helvetica are not included in the Mac OS X 10.4 system).