The nook already supports eBooks written in western languages (like French, German, Italian, and Spanish). It does not support characters from non-western alphabets yet but it could be updated to do so. It also supports PDF documents in different languages (and different character sets as long as the font is embedded in the PDF).
The Android platform the nook is based on is very friendly to internationalization.
At some point when B&N decides to sell the nook internationally (like the Kindle) it has a platform setup to handle it.