The ColdFusion 10 documentation on Updating Your Database has a section on Database-related enhancements in ColdFusion 10. That page mentions that there is now support for CF_SQL_NVARCHAR among others, but with no details about them. Additionally, the cfqueryparam documentation hasn't been updated to include their existence.
The ColdFusion 9 documentation for cfqueryparam mentions that CF_SQL_VARCHAR maps to varchar in MSSQL. This is true unless the ColdFusion Administrator datasource settings has the String Format setting enabled. In which case CF_SQL_VARCHAR maps to nvarchar. This poorly documented feature is a hack which can cause performance issues within ColdFusion.
So it's great that they have introduced CF_SQL_NVARCHAR, but it would be good to understand how it works. It is simply an alias for CF_SQL_VARCHAR making it pointless? Does it always send strings as nvarchar? If so, does CF_SQL_VARCHAR always send in varchar?
I would hope that for backward compatibility's sake it is implemented as such:
If String Format is enabled CF_SQL_VARCHAR