SharePoint 2010 supports multiple languages per site, and you can check that the site template supports MUI by using the SPWebTemplate.SupportsMultilingualUI property. Then, you can use the SPWeb.AddSupportedUICulture method to add a new culture.
For more information about localization, see the following MSDN topics.
- Localizing SharePoint Solutions
- How to: Localize a Feature
- Walkthrough: Localizing a Visual Studio SharePoint Application
- Localizing the User Interface
- Walkthrough: Localizing a Web Part
Mary Lee, Programming Writer.