In our web.config one of the most individual sections is the <virtualPath> one, since we have a custom of placing the VPP folders one step below the siteroot, to make it easy to keep track of everything in the project.
Since most developers have their own folder organization, this section differs between developers. Which means that when a change has been made to web.config by one developer and checked into svn, the others have to re-edit web.config to restore their own paths.
Because of this it would be useful if the virtualPath section could be broken out to a "virtualPaths.config" file with the help of configSource, like you can do with other sections of web.config. However, it doesn't appear to be supported as far as i can see.
Is there some way this is possible to do already, or is there a chance that it will be implemented in the future?
This isn't an answer to your question, but more a suggestion to project structure :)
You should never commit .config files to subversion (or sourcesafe,etc). You should create .config.template files instead. All changes are merged into the template file and commited. The other developers merge the changes they need to their local copy whenever there's a new version of the .template file available. That's the easiest way to keep individual settings :)
And, to compare files/folders/etc you should try Beyond Compare. It's an awsome product :-) (http://www.scootersoftware.com/)