There's always something new to learn about software localization - for instance
Microsoft's approach to creating "Universal" or "Neutral" Spanish Translations.
I suppose if you asked the 'person on the street' they might think there _is_ only one Spanish (or French, for example) language - at the other extreme if you asked a Mexican, Bolivian (or New Caledonian/French Canadian) they would probably insist their native tongue is quite distinct from that used in Spain (or France).
When faced with localization in these languages, the two obvious solutions might be:
* use the 'original' language and expect it to work in all other countries; or
* localize into each and every 'dialect' of the language to ensure you do not alienate customers in each country.
The (think outside the square) solution is, of course, to merge these two ideas -- purposefully structure the language you use so that it appears natural to ALL speakers. That's actually a lot harder than it sounds, but reducing the number of software versions you have to ship from ten to one (eg. in Spanish) certainly appears to make it worthwhile. This i18nguy article about Microsoft discusses the concept of “Universal” or “Neutral” Spanish and particularly Latin American Spanish (es-americas).