An update to the Inventory is being released gradually to all players.
One of the primary differences is the ability for other players to see the quantities of items in your inventory.
However, if you have concerns about the privacy of your inventory, there is also the option to hide the quantities from other players by clicking the Change to private link at the bottom of your Profile page.
The following is unchanged from the old inventory layout.
If you have any questions about the usage of the new inventory layout, please watch the following video: http://www.youtube.com/watch?v=WFaQ1XOpVNQ
If you have any feedback or suggestions about the updated inventory layout, please go to http://getsatisfaction.com/mafia_wars/ where players can discuss and vote on ideas. Popular ideas (as determined by fellow players) are directly relayed to the design team for consideration.