I like this approach also because of security reasons. It could make application sand boxing easier if it can only read/write in its local directory and the use

I like this approach also because of security reasons. It could make application sand boxing easier if it can only read/write in its local directory and the users directory. Getting rid of the dll nightmare is a very good point. I'm also very impressed by the method used by Apple to support multiple machine codes into a single app. On the other side, application scanning at boot time is not a very exciting strategy. Why not binding this with the file index like tracker that a good OS should have ? The index would be updated in background when files are created or deleted and so will be the application locator and document type binding. I am more am more convinced that this is a new direction to go in addition to make the OS the most lightweight possible and eventually generalize virtual machines. It is hopeless to secure current windows PC against becoming zombies.