The Circles feature in Google+ (plus) has some really useful functionality in terms of whom you want to share your content with in the form of closed groups. This is something totally opposite of what Facebook allows.
However, the interface where you create new Circles and add friends to these circles is really cool. Now, CircleHack aims to bring the same Circle Experience in Google+ to Facebook. You can try CircleHack right away or check out these screenshots below before starting.
All you need to have is a Facebook account in order to log into CircleHack and after you grant the necessary permissions yo will get to see Google Plus's Circle magic inside Facebook. One thing we would want you to know is, CircleHack is just a way of displaying your Facebook friends inside various Facebook lists. CircleHack won't help you in achieving the functionality that Circles add to Google Plus.
The developer of CircleHack has made the project open-source and can be found at: github.com/voloko/facebook-circles