Thanks for posting this. It does look very interesting. Even without the app, as they noted, it's a good technique to remember. Instead of ignoring or suppressing worrisome thoughts, working with them by changing their focus may be helpful.
edit: I read the article without looking at the app. The app hasn't been updated since Dec 2013. At the Googleplay store, the reviews are not good for the stability of the app. It's a promising concept, but it might need another app.