Total shot in the dark here, but if there is a delay between the US release the Europen release (or for other locales), I'd bet it's due to translation. When they make the final build of the English version, they'll have their translators look over the final text changes and update the French, Spanish, German or what have you (anyone know what languages NWN2 is planning to support?).
Admittedly, one might wonder why the UK version would be delayed as well. I suspect:
- Colour, neighbour, realize, in hospital, and etc.
- EU law or agreements with Atari's EU distributors.
-Throbblefoot