Here's a bit of coincidence (these byte/text/language posts were scheduled a while ago) - MSDN Magazine has an International Applications article that mentions the impact on language on other text processing operations, such as comparisons, sorting and case changes.
And for extra coincidence points, the example the article gives about sorting using traditional Spanish or modern Spanish rules is exactly what was illustrated in an older post about Parameterized sorting in XSLT.
Which I guess just goes to show that these things do matter, and developers are paying more attention to them, and hopefully we're all creating better software as time goes by.
Of course, no post such as this should finish without posting to Michael Kaplan's great blog at http://blogs.msdn.com/michkap/default.aspx.
I've written in the past about XML and languages, and why you might be interested in being aware of the