Parametric Technology Corporation - PTC
3D Mechanical Design Automation and Product Data Management Solutions
They use Tcl/TK to configure portions of Windchill, their enterprise level data management and process/workflow application.
They also use Tcl/TK to setup/configure/administer Pro/INTRALINK, a Product Data Management solution that uses an Oracle database for their 3D Mechanical Design/Automation Product called Pro/ENGINEER.
Tcl/TK has been used actively for several years, but it is not disclosed or marketed by PTC.