Zynga has released the 411 page for "Crack The Safe" version 2.
Please read on..
(If you don't have this feature yet, please read my blog post here : Where Is My "Crack The Safe" Feature?)

Crack the Safe 411 & FAQ

Updated 04/12/2011 at 17:29

Crack the Safe 411 & FAQ Here is your chance your build your Mafia and add some valuable loot to your arsenal by completing the Crack the Safe challenge.  This challenge is easier than you might think.  In order to receive the prized mastery reward all you will need to do is complete the following steps.  Make sure that you have the Mafia Wars game installed  ‘Like’ Mafia Wars on Facebook  Increase your Mafia by adding 5 new friends to help  Allow Mafia Wars to publish to your news stream After each step is completed you will receive one of the following Mastery items. Charging Bull Animal Superior 52/97 Half Rack weapon Superior automatic 97/60 Bottle-nosed Dolphin  Animal Superior aquatic 98/54 Dolphin Submarine Vehicle Superior aquatic 55/98 When every step has been completed you will receive the final Mastery item: Q:  When did this event begin A:  This challenge was slowly rolled out to our players starting on 4/7/11 Q:  How come my friends can see this event but I can't? A:  As with all of our previous events and challenges, this will be a gradual release to ensure stability within the game.  (Not all players will have initial access to this challenge.) Q:  When will the event end? A:  There is currently not a date scheduled for this event to end. Q:  How many times will I be able to complete this challenge? A:  There is a limit of 100 times that this challenge can be completed.  If you reach this level your Mafia is sure to rule supreme. Q:  Can I purchase these items from the Marketplace? A:  No.  These are limited edition items and they are currently only available by completing this challenge. Source : Zynga Customer Support