MKBL :
It sounds like a 19th century thief making a copy of an original key to a lock, rather than "hacking" in IT sense. Key to this "hacking" is to get the original key, the finger print of the owner of the phone. I'm not downplaying the work of the group, but the title can be misleading.
The point is, if you steal a phone without knowing the password, you would have to actually hack it (meaning a lot of knowledge on the phones security), spy on the person to find out their password or actually know him that well that you would guess it. That was a lot of trouble for some random person's phone and you would do it only if there was something else involved apart from just re-selling the phone (like acquiring certain data). Now, with the fingerprint scanner you have, as we 've read, a purely technical method to acquire the "password" that does not require any knowledge of mobile security and algorithms, not to mention a phone that will probably be covered in the user's fingerprints...
People need to understand a few things about security:
1) No one measure alone is enough. Usually, if you have a building with biometric security measures, there will be different ones, or combined with other measures (i.e. fingerprint scanners, along with facial recognition and a smart card).
2) Fingerprints on consumer devices are not used for extra security. It's simply an easy way to generate a random pattern on which the password will be based. Something that the user can't forget. It's a matter of convenience, not security.
3) Last but not least, EVERYTHING is hackable. There is a constant race between hackers and security systems and there's no sign it will ever end. The only thing that really defines how safe you are, is how much of a target you are. If there is enough interest for your data/information, be sure that people will spend time and money to get to it.