iFrames in the Real World
Because currently used browsers support iFrames, you can use them directly without any added configuration or setup effort. The example application demonstrated how with minimal development effort iFrames can make fetching data from the server transparent to the user, thus relieving users from having to wait while the application fetches the data.
Such a technique can be of great help with more complicated scenarios as well. In fact, I see many uses for iFrames in real world applications, including as an alternative for Applets in some cases. For example, the traditional ticker example built with applets can be easily done with iFrames embedding a JSP page.