> What we need is to add an application list to filesystem ACLs and then have security groups like Video and Finances which contain apps. Because GIMP should be able to access your photos but not your accounting spreadsheet.

This isn't that hard in a technical sense. But I very much doubt you can get the casual users to actually do that. They'll just end up with one giant group, because it's the easiest and doesn't require understanding the concept of security boundaries.

Basically, it'd be Vista UAC prompts all over again.