This blog is updated daily..
A general description is here.
Under some circumstances ‘package.skeleton()’ would give out progress reports that could not be translated and so were reproduced by question marks. Now they are always in English. (This was seen for CJK locales on Windows, but may have occurred elsewhere.)
There is experimental support for _link-time optimization_ with ‘gcc’
4.5.0 or later on platforms which support it.