I'm leaving on Sunday, so these days I've been quite busy preparing everything for the Boston Drupalcon 2008.
To the question "Will Drupal 6 be multilingual?", I just can say that it will be "more multilingual than Drupal 5", but really cannot give a straight "Yes" answer as it is not really fully multilingual because there are a big number of parts that cannot yet be localized or translated.
This is the latest try and our last chance for Drupal 6. There's a very minimum set of patches to at least allow contributed modules to hook into the right places of Drupal core and have a fully multilingual Drupal 6 without using dirty hacks or core patches in contributed modules.
Update: Preparing a DEP draft for implementation in Drupal 4.8
We are in the proccess of adding full multi language support to Drupal.