How to show the complete title of an app?
Sorry, there is not way to do this.

I believe that some launchers may wrap titles, but I can't think of any that do.

As per dymutaos' comment:


  ADW wraps the titles of apps. They wrap it to a second line, and they make the second line smaller in order to fit within a certain space. Though if the name is really long and doesn't fit within 2 lines, it still gets truncated.