This is old news but I often get questions about it. In Mafia Wars, not all promotions are rewarded equally. There are currently 4 different Promotion pop-ups with 3 different types of rewards. Everybody gets 5 Skill Points for all promotions and one Reward Points for every even level they are promoted to. Some players get Hired Guns as well. If you have a large mafia, hired guns are very useless. All they do is count towards the number of mafia members you have. They can be very valuable to players who don't have a mafia of 501 as they will be used in the combat equation. Your overall equipment attack and defense scores are your highest scoring equipment items multiplied by the number of mafia members you have up to 501.Mike Nestor sent me the following images from some of his accounts showing the different promotion screens.
0 Hired Guns
1 Hired Gun
2 Hired Guns
The Mafia Wars Maniac Blog. Read more about this special pop-up and a tutorial for new players by clicking the link.
(image from the Mafia Wars Maniac Blog)