[NOTE: 31 July 2007, the tool is available again at its new URL: http://www.microsoft.com/downloads/details.aspx?FamilyID=e4588c5e-8f21-45cc-b862-38df8d9bd528&displaylang=en]
The Microsoft Locale Builder Tool Beta 2 is now available for download. This requires Vista to run.
If you're interested in custom locale data or locales that aren't supported by Microsoft, I'd encourage you to download the tool and take a look at custom locales. I've previously blogged about custom locales, and its been possible to create your own with Microsoft.Net V2.0, but the Locale Builder tool makes it a lot easier.
Let me know how this tool works for you, and thanks to the Locale Builder team for making it happen!