I remember going to the launch of AutoCAD Designer. Mechanical Desktop replaced Designer and now, although some with much more knowledge than me might argue this, Inventor has replaced MDT.
Engineering Education for the Mechanically Inclined: Farewell old friend
Autodesk Mechanical Desktop 1995-2008
Some of you may have read on the web or received an e-mail notification announcing the discontinuation of Autodesk Mechanical Desktop after the present 2009 release....
Note: I've backdated this post to about the time it was written as found it lurkng in my drafts.