Application Foundations for SharePoint 2010

Microsoft.Practices.ServiceLocation.dll, Microsoft.Practices.SharePoint.Common.dll

http://msdn.microsoft.com/en-us/library/ff798371.aspx

sharepoint resource folder _cts

http://office.microsoft.com/en-us/windows-sharepoint-services-help/change-a-site-content-type-HA010097877.aspx

http://blogs.msdn.com/b/uksharepoint/archive/2009/10/15/how-to-include-document-template-files-in-content-type-features.aspx