Hello all and happy new year!
      I got an update regarding the electronic lock with magnetic keys.
      The lock they are using in Athens hackerspace is the cisa
      elettrika [1]
      It is connected with an Arduino that checks the validity of each
      i-button that every member has. If the i-button is ok then it
      opens the door through a 12 volt relay. 
      The i-buttons cost around 2 euros max.
      
    
    
    [1]
      http://www.electriclock.net/acatalog/cisa-elettrika-rim-locks.html
    -- 
-p