Howdy,
I have been working on a program like you speak of for almost a year now. You
can read all about it over at http://www.gamemakerstudio.net and see a video of it in action here http://www.gamemakerstudio.net/data/NewProject.wmv
Believe or not XNA fits very well for a program like this
and I even use it in components which then directly translate into the game
since both are XNA it works very well. I will have a whole set of C# and VB code
to build an RPG up and running very soon. As well as components like in RPG
Maker XP that let you develop and management game content.
I must give kudos to the XNA and the whole .Net Environment.
It is uber friendly for developing a program like this with the whole MSbuild technology
and the content pipeline all of which anyone can easily support for more
complex content management.
If/when deployment and package for the general public comes
around it will make the whole solution complete with very little work on the
part of the developer.
I would be happy to talk to people wanting to develop a program like this and explain all the little ups and downs I had.
Take Care,
Near