Generally pre-programing refers to patching the console and setting up a few basic cues, effects, chases, scenes, submasters, and/or palettes depending on your console. This is generally done with off-line editors. Just about all my shows are pre-programed in this fashion, so I simply have to load the show from disk or USB drive and start the fun programing. It is a great time saver.
The type of pre-programing islanddj is talking about is done with virtualization software, like Elation's Magic 3D Easy View, WYSIWYG, or Vector Works Spotlight. Major shows like the Olympics are programed in this fashion because the designers and programmers don't have time to take up a stadium with a full production set for weeks to program. They instead program the whole show without any equipment besides the console(s) and the computer(s) with the software on it.
It is also a great to show people what something will look like before they ever have to rent/buy it. They can also do paperwork as well as light plots. Truly a powerful tool in the right hands.