Google Docs now supports translation into 42 languages: "
Google has added a 'translate document' option to the tools area of Google Docs. This lets you translate the text of any document to 42 languages. You can either replace the original file with the translation or copy the translation to a new document which you can share with collaborators or export as a DOC, HTML, PDF, RTF, TXT, or OpenOffice.org file.
You could also use the tool to import documents written in another language and translate them to one that you speak. Of course, the machine translations won't be any better than what we've come to expect from the Google Translate web service. But garbled machine translation is better than no translation... usually.
Translation is available for documents, but not for spreadsheets or presentations.