The DevX website has recently posted this tutorial - a look at simple internationalization for your website.

If you develop Web applications that have an international target audience, then you have to take internationalization into account—a process that includes avoiding date/time or currency confusions and delivering all text pertinent to the user interface in the user's preferred language. Applications that can grow international traffic and improve revenue must respect their clients' needs.

They use the I18N PEAR package to handle most of the hard work and include the howto on grabbing the package, the structure and how to use it to get a country name from a code, work with the translation of numbers, currency and changing up date/time strings.