Why would you think you would get them on your Mac? Do you have a FaceBook app on your Mac that no one else does? The only reason you get notifications on your phone is the FB app you probablly have on your phone. The notifications you get on your phone will not tranfer over to your Mac.
Why would you think you would get them on your Mac? Do you have a FaceBook app on your Mac that no one else does?
Errr, Yes he does have an app on his mac - Notification Centre!!!
On Mountain Lion Notification Centre does notifications for both Facebook and Twitter.
In answer to the OP question, have you added your Facebook username to System Prefs > Mail, Contacts & Calendars?