I`ve just finished translating the WordPress K2 theme into Dutch / Nederlands (nl_NL).
The translation works on K2 1.0.2 or higher.
I`ve decided to cooperate with James John Malcolm, so we`re both taking care of the translation.
To use the translation, choose the language in wp-config.php and place the files above in /wp-content/themes/k2/languages/
If you notice any mistakes, feel free to reply and i`ll fix them as soon as possible.