Many Social Networking Scripts are there but I dont know if there is a one with the Same Features as FB , PhpFox Dolphin These are the popular ones there are Free as well as Paid versions available for them.
There are only just a few good social networking scripts around. Actually 3 well known and solid, they exist for many years already and have good support too and private forums. phpFox - http://www.phpfox.com (the best of the 3) Social Engine - http://www.socialengine.net Jomsocial - http://www.jomsocial.com (this is a Joomla component, Joomla itself is free)
Like ilook says: phpFox will be your best bet. It is a feature packed script developed over many years with a big community that provides support, mods and custom work!