Which Drupal clients allow editing of non-Blog nodes?
Depending on how much work you want to do, you could write a custom interface in HTML5/JS, then wrap it in Titanium (link below) or Air
http://www.appcelerator.com/products/titanium-desktop-application-development/

Then use the Services module http://drupal.org/project/services as the API - you might want to extend the functionality yourself

Also, not sure if this is for a particular client requirement. But if it was just node creation without opening a browser you could consider this http://drupal.org/node/1045918

...Or you can pull out the necessary code from the blog api and extend :o)

Either way I've got no simple answer I'm afraid