The new File Geodatabase API provides a CreateGeodatabase method. Since the API only supports 10.0 databases at this point, there is no immediate need to specify a FGDB version. However, when ArcGIS 10.1 is released, it will be useful to specify which version of file geodatabase is to be created.
I propose an overloaded CreateDatabase method that would take a parameter that specifies the geodatabase version to create (10.0, 10.1,...).