According to Nokia, adding support for Silverlight will extend opportunities for developers to create rich, interactive applications that run on multiple platforms in a consistent and reliable way.
This is definitely a scoop for Microsoft.
This deal will give Microsoft access to Nokia's millions of mobile users. Microsoft could easily leverage these users for their any future mobile communications business.
Moreover, with Google's already announced strategy in wireless communications with its mobile OS Android, this is just a clever move my Microsoft to make sure that they have a say in the future mobile business.