There still is the problem with the Object Mapper not showing up in the tools menu of my German VS2005. That is because the menu is called "Extras" in German, not "Tools". As I didn't want to install an English VS, I decided to see if I could get it running. Well, I did. I had to do some reverse engineering using .NET Reflector for this, hope that won't invalidate my license ;)
The problem was that your addin code looks up the name of the menu in a ressource file which is only having English and Japanese names. Not sure why, probably that has been generated using a beta version of VS. When I created a new addin project, I got such a file generated with a lot more languages - probably all available VS localizations. Essentially I built a new addin using your code and "my" resource file. That works quite well, I did not yet encounter any other issues...
I attached the new resource file (I'm sure your VS can generate one automatically as mine did, just in case...), would be nice if this would be included in your next release :)