Twitter has started gathering the names of the apps you have on your phones/tablets. The new feature is called “Twitter app graph.” They are claiming they only gather the names of the apps rather than the data stored within them.
According to Mashable, this snooping only happens if you are using their mobile app. If this is correct, you have 2 options if you want to continue using Twitter without allowing them to gather this data:
1. Use Twitter from a browser rather than installing their app.
2. Follow the opt-out procedure here.
Twitter seems to be doing this so they can personalize the ads they deliver to you based on the apps you have installed. It is up to you to decide whether they have any business knowing the names of the other apps you have installed on your mobile device, and what you should do about it.