Pay attention: The practice of news handling that is described here has been obsolete for some time now, as they are being fed automatically from Planet GNU (http://planet.gnu.org). Nevertheless, the information below is accurate to the extent that the support for the old-fashioned way is still available.
The GNU website has infrastructure for supporting “What’s New”, also known as “GNU News”. Entries are added in a special plain text file, server/whatsnew.txt and are used to build server/whatsnew.include and gnusflashes.include. The former is used by server/whatsnew.html, while the latter was included in the homepage.
GNUN has additional rules for building whatsnew.pot, which contains a combination of all necessary strings for server/whatsnew.lang.html, server/whatsnew.lang.include and gnusflashes.lang.include. There is nothing unusual in this POT file, so it should be translated like any other. When you commit whatsnew.lang.po, it will be used to generate all three localized files.
Note that localized RSS feeds are not supported on purpose, as it would be annoying for subscribers if new items appeared in English and then, again, as a translation.