Well, the application icon in the Dock will bounce, or, if you have bouncing turned off, the little black triangle below the Dock icon will fade in and out while the program is loading.
If you're talking about files opening and not programs launching, then once you double-click the file to open it, a rectangular animated "outline" of the file will scale larger to fill the screen (understand? I don't know if that came out right) to let you know that you've double-clicked it... then the whole scenario I described in the first paragraph will happen, unless, of course, the application that handles that kind of file is already open.