FYI - The My First AutoCAD Plugin tutorial is now out of Beta, which means we've added the missing videos and fixed a few bugs. You'll find the tutorial here: http://www.autodesk.com/myfirstautocadplugin
. And you can watch a (slightly tongue-in-cheek) promo video here: http://www.youtube.com/watch?v=5a50QULamuU
Many thanks to all who gave feedback on the Beta - especially to Gile for fixing the transformation matrix calculation in the bonus plugin. (I've not posted C# translations of the VB.NET projects yet, but versions of those are available from the original post on this topic on this forum - I think Gile did those translations too ).