Parametric Technology Corporation - PTC
http://www.ptc.com

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 configure and administer ''Pro/INTRALINK'', their Product Data Management solution for ''Pro/ENGINEER'' -their 3D Mechanical Design/Automation Product.

Tcl/TK has been used actively for several years, but it is not disclosed or marketed by PTC.