Thanks for the correction – I fixed it in the article.

I’ve seen some comments about ppa-purge in the Bumblebee installation instructions, but I didn’t have it installed (I actually didn’t understand it is something that I need to install until your reply – I thought its just something that does no longer exist in 12.04 🙂 ), and it worked fine for me without doing any of that. But thanks for sharing another success story!