This blog is updated daily..
A general description is here.
Collating (e.g. <) and sorting is done in UTF-8 where one of the items is in UTF-8. It seems that MSVCRT's collation order can be different in widechar and in ASCII, so this can lead to inconsistencies.
The size of the Rgui buffer is now set in characters not bytes (the difference only matters in CJK locales), but for backwards compatibility the entry in Rconsole is still called 'bufbytes'. The default has been increased to 250,000 chars (0.5Mb).