It's using an old CSS history hack. The part where it asks you to "see where you friends have been" is a complete sham. It just wants to get your facebook crede

It's using an old CSS history hack. The part where it asks you to "see where you friends have been" is a complete sham. It just wants to get your facebook credentials to viral-market itself across your address book. The best it could do is cajole your friends into using it, and then surreptitiously tell you where it thinks they have been .. a gross violation of privacy.