There are language packs for PunBB 1.2.x, but the anpoop plugin does not so I am willing to add other languages to this forum on request if the requester provides me a translated version of the anpoop language file:
<?php
// Language definitions used by the ANPOOP-mod
$lang_anpoop = array(
// Common
'New message' => 'New posts',
// User profile
'Option ANPOOP' => 'Set your options for viewing "New posts"',
'ANPOOP info' => 'You can change options for viewing posts.',
'Nick link' => 'Show nick in post as link.',
'Button reply' => 'Show link "Reply", after all new posts in topic.',
'Moder ip' => 'Show user IP-address in post (only for moderators and admins).'
);
Automatic language guessing is not possible with PunBB afaik.
Patches welcome 
We already have them (see the German and Russian forums.
I don’t see a possibility to do that, but you can use RSS feeds and ‘all new posts on one page’ instead. There is also the possibility to receive an email when someone posts to a topic that you’re interested in. You will have to add a valid email address to your forum profile for this to work. Lastly, there is also the email digest plugin for punBB. It seems very flexible and lets you choose whether you want the digest daily, weekly or monthly and from which forums. Perhaps I should add this plugin anyway…
Unfortunately this version of PunBB only supports 2 levels…
Interesting, I’ll look into that one.
Sorry, I don’t understand…
Yes, very useless 
Also very interesting, can you have a look at mediawiki and try to find out if such a thing is possible with forums (and PunBB in particular)?
A mail2forum (and back) gateway has been looked at in the beginning when this forum was setup. The consensus in the community then was that such mechanisms rarely work well and that it generates a lot more traffic on mailinglists and forum. There is also a bit chance that it will become unclear who is responding to which message and that mailinglist/forum threading will be broken. So, although it looks like a very good idea, the technical hurdles are quite high.
I know that PunBB is not the most advanced piece of forum software, but it’s quite bug free (no spam and such) and lightweight. Moving to another brand of forum software is possible if it’s easy for me to write an external authentication plugin that can do HTTP authentication against the OSM database or if someone can provide such a plugin.
Besides all the features, PunBB uses very low amounts of bandwidth. As there are at least 3.000 unique visitors every day and 15.000 pages served every day this is important. The forum currently uses about 4GB of traffic each month and anything more then 6GB will force me to search for another hosting package.