In order to use this project you need to add a reference to the
"Microsoft SQL Server System CLR Types". 

If you have SqlServer2008 (Express) installed on your machine you'll probably find in somewhere 
in the installation path of it. On my machine the path is:
C:\Program Files\Microsoft SQL Server\100\SDK\Assemblies\Microsoft.SqlServer.Types.dll

If you do not have SqlServer 2008 on your machine, all you need is download some files
from the "Microsoft SQL Server 2008 Feature Pack, October 2008":
http://www.microsoft.com/downloads/en/details.aspx?FamilyId=228DE03F-3B5A-428A-923F-58A033D316E1&displaylang=en

Look for "Microsoft SQL Server System CLR Types"

Enjoy
FObermaier