Linq-to-Sql is officially a legacy ORM: http://msdn.microsoft.com/en-us/library/ms178359.aspx#orm.
LINQ to SQL is a legacy ORM that Microsoft provides.
Also
Microsoft is investing minimal efforts to enhance it
Meaning: spatial data types will never be supported by Linq to Sql. That's why the old answers still apply and will always apply. Move to Entity Framework 5 or higher for an ORM with spatial data support.