Note that Nagao Shijo also announced an "Object Tcl" at http://www.hf.rim.or.jp/~nagao/object-tcl-2.0-snap.tar.gz ; I'm uncertain whether that was a derivative of David Young's Object Tcl or not.
A simple script only OOP extension for Tcl. This extension provides class with multi inheritance and configuration methods which is similar to that of Tk widgets. The OOP features are constructed with minimal system commands that has simple interface and proper error message handling, minimal quirks and minimal overhead. It is very easy to create a new combined widget from original widget set. The namespace facility in Tcl8.0 is completely supported by version 2.0. The system works on both Tcl7.* and Tcl8.0. Currently, the only development snapshot is available from the WWW server.