NullableTypeEx.cs

public static class NullableTypeEx
{
    public static Type UnwrapIfNullable(this Type type)
    {
        return type.IsNullable() ? type.GetGenericArguments()[0] : type;
    }

    public static bool IsNullable(this Type type)
    {
        return type.IsGenericType && type.GetGenericTypeDefinition() == typeof (Nullable<>);
    }
}