A minor changes to ArcGIS Online is happening today.
On May 23, 2007, the services on ArcGIS Online will be organized into a basic folder structure. This change will help make ArcGIS Online services easier to locate when you add them to your maps and globes. You will need to update the service reference information in any existing maps, globes, and Web applications that use the affected services.
Not all services will be removed from the root (and as of this post they haven’t removed any yet, just duplicated them into the new folders). Of course this means you’ll have to update your links to the new files and ESRI has posted instructions (strangely as a news item and not a KB or technical article) on the ArcGIS Online site about how to do this.