When most people think of the GPL, if they think of it at all, they tend to think of Linux and perhaps other operating systems.  However, there are many benefits to using the GPL for programs on a smaller level.   For example there is a Go Application in Facebook.  This programmer could have gone through the near impossible headache of creating an implementation of Go.

However, as Wikipedia mentions, it is very tough to create sofware to play go, “While the strongest computer chess software has defeated top players ( Deep Blue beat the world champion in 1997), the best Go programs only manage to reach an average amateur level.”  This has to do with the high complexity level of the game’s strategy.