When I tried it, I did not get any icon flying across the screen. [Note: This is a problem with these special effects. They don't always work the same across different browsers and different platforms.]
However, to make an icon fly across the screen, you'll want to use DHTML which is just Javascript modifying css values. In this case, the css value is the position of a div tag that contains the flying icon. You use a loop in Javascript to repeatedly change the value of the X coordinate in the position of the icon's div tag and watch it fly. DHTML is sometimes confused with Ajax because they are similar... but just making the icon move is DHTML.
Now I did notice that clicking the icon causes an event to happen (some communication is happening with the server) and then the "+ Add to Event" icon grays out all without the page refreshing. The part where clicking the icon sends information to the server without the page refreshing is Ajax. Making the icon gray out is DHTML (using Javascript to change the src information on an image tag). So you're really seeing a combination of Ajax and DHTML.
