Marshall sez: looking at the code in trunk, it appears that this patch has been (more or less) applied.
I'm not sure about the constructor call to std:locale() for each character, though.
{{
while(beg != end) {
#if !defined(BOOST_DATE_TIME_NO_LOCALE)
ss << std::use_facet<std::ctype<wchar_t> >(std::locale()).narrow(*beg++, 'X'); 'X' will cause exception to be thrown