While exactly how to implement ArcGIS Online for an organization such as a college is still a bit murky, I have a much clearer sense on the process of taking data from ArcGIS for Desktop and publishing it as a service. I spent an hour and a half in a hands on lab working through a cookbook exercise to publish first a map tile service (pre-rendered tiles to use a background) and then a feature service (actual vectors that have attributes and can be edited). At this time there are the only kinds of services that can be published via ArcGIS Online subscription accounts.
While the process is relatively simple, there is still quite a bit such a user needs to know including the range of scales when the map tiles will be visible, how to correct errors when the service is created, and how to navigate ArcCatalog to access services. I should note that I had a bit of trouble because I’d not touched ArcGIS for some ten years and I’d not touched a Windows machine in about five. Still, once I got the the first service published and learned some vocabulary for the different interface objects in ArcGIS, I was able to get the second service published with relative ease.
That said, I can see how less experienced GIS users might still get confused about visiting ArcGIS.com/home (which says ArcGIS Online on it) to find services of interest and then have to decide to open them in ArcGIS, ArcGIS Explorer (as we did) or ArcGIS.com Map Viewer.
Some in my lab had a tough time remembering to change the search tool to search all content, not just Web content, while others tried to add a definition of a web service instead of the web service itself to a map. In short, we found a number of places where we could “mess up” in creating the services and then trying to use them to create simple maps.