indiePub has published an article about English as the de facto language of game development. The article includes quotes from several indie game developers.
From the article:
"Dutch people are all raised to speak English well, much more so than French developers, so it is no problem at all," explained Ronimo Games' Joost van Dongen (Proun), who lives in Utrecht, Netherlands. "I actually think it is really great that there is one language in which we can all communicate, instead of having these islands of people who cannot talk to people on another island because of the language barrier."