As you may see from the domain name in link, it is to be downloaded from NOKIA's servers. So it is "more or less" the official version. You are also able to use Navifirm to download this from NOKIA.
But yes, on the site where I would expect such update to appear, it is not listed. So dear users, that is the official NOKIA support strategy for the best device they ever abandonded.
I wonder what will happen to us Maemo users in 2013?