Sphinx

Sphinx has gettext support:

http://www.sphinx-doc.org/en/stable/intl.html?highlight=gettext

Lektor

The upcoming new Tor website uses Lektor.

There's a PO plugin for Lektor but Tor does not use it. Ask hiro for details.

Lektor will soon be in Debian.

Hugo

See Birger Schacht's PoC conversion.