This blog is updated daily.
A general description is here.
‘iconv(to = "utf8")’ is now accepted on all platforms (some implementations did already, but GNU ‘libiconv’ did not: however converted strings were not marked as being in UTF-8). The official name, ‘"UTF-8"’ is still preferred.
Finalizers are marked to be run at garbage collection, but run only at a somewhat safer later time (when interrupts are checked). This circumvents some problems with finalizers running arbitrary code during garbage collection (the known instances being running ‘options()’ and (C-level) ‘path.expand()’ re-entrantly).