I really hate having the OS in spanish (as probably you don’t know, I’m in mexico), because the translation is made by spain, and I really hate the style. So every OS I have is in english, the problem became in pages, because it gets the global language settings.
But sometimes I want to write in spanish, so I managed to put several languages in pages, so you have to select the desired text to be written in a different language, and in the inspector > text > more you can have the language…
see the screen:
http://www.macosxhints.com/article.php?story=20050206093713234