Small quote from the press release:

"Microsoft Corp. and Nokia today launched the first application from their alliance around mobile productivity, Microsoft Communicator Mobile for Nokia devices. This new unified communications client connects directly with a company’s communications systems to streamline mobile collaboration. Owners of a number of Symbian-based Nokia Eseries smartphones can download the English version today from Nokia’s Ovi Store, the easiest place to get content on their Nokia devices."

Complete Press Release on Microsoft.com