moshu:
1. Yes. the wordpress.mo file is the language you want to install.
It’s like every other mo file on a Unix system, they are named after the application and in the LC_MESSAGE directory of the language.
so de_DE.mo has to be copied to
wp-includes/locale/de_DE/LC_MESSAGES/wordpress.mo
fr_FR.mo to
wp-includes/locale/fr_FR/LC_MESSAGES/wordpress.mo
and so on.
2. Yes, this is the new content of wp-l10n.php.
Tested this on WP 1.3-alpha-4, but wp-l10n.php hasn’t changed since 1.2, so this should work for 1.2 as well.
3. I don’t really know if gettext support is compiled in PHP by default.
However it is compiled in by default on Debian, maybe other distributions also. So I think there’s a real change of having gettext already compiled in in a virtual hosting environment.