The MSDN and Volume License Media for Exchange 2010 SP1 include the latest versions of Client and Server Language Packs that were available at the time of release. These are the same versions that are distributed with the Exchange 2010 SP1 package available on the Microsoft Download Center.
Installing Exchange 2010 from the MSDN and Volume License media will automatically install client and server language support for all languages available on the DVD. The Unified Messaging Language Packs used by the Unified Messaging Role are also included on the DVD for convenience but will not be installed automatically by setup.
For more information, please visit Post Installation Tasks or UM Language Pack Installation.