Language is Critical to Usability
Did you catch usability guru and world traveler Jakob Nielsen's latest Alertbox, "American English vs. British English for Web Content?" It's a good reminder that language and the use of language to communicate is not always as easy as we may think, especially if we are writing (or conducting usability evaluations) for clients in other countries.
Tomlin, Craig. Useful Usability (2008). Articles>Usability>Writing>International