How do you perform robbery's on Mafia Wars on Facebook?

Answer 1

At present, you can't. Robbery used to be available when all players were able to obtain Properties. When Properties were replaced with Rackets, after a short delay Robbery was disabled "for upgrades". Zynga is still working on what to do about Properties, Rackets and Robbery, or hasn't yet released its upgrade. Players with properties have been promised they won't be taken away automatically but they will be given a very good deal to trade them in. Since robbery was only suspended and not removed, it is likely that it will eventually be possible to rob someone's Rackets, but at present this is not possible.

When Robbery existed in the game, it could be accessed from a player's Profile page - an option "rob this player" appeared along with "attack", "sucker punch", etc.