With over 9 million monthly users on Facebook last month, and nearly 12 million total players on MySpace, Mafia Wars is one of the most popular game on social networks. Today, players can join the underworld on the go as Zynga has just released the iPhone version of Mafia Wars.

Mafia Wars is Zynga’s third title released for the iPhone after Live Poker and Scramble Live. As it stands, the new app is available for any iPhone or iPod Touch, and is free. However, Zynga says that the game will also have premium versions ranging anywhere from $10 – $40 that will be made available soon. Additionally, Mafia Wars for iPhone is not launching with Facebook Connect integration, though we’d expect it to be released soon.

With Mafia Wars for iPhone, Zynga is focusing on what they know best rather than implementing totally new ideas for the mobile platform. Users can expect the same familiar game play for the iPhone version: Build up your families, manage cash, health, energy, and stamina, gear up, and take out other players. However, while these elements are the same, players can expect a whole new look for the game, as it contains brand new art, animations, and sounds while they track friends’ progress through real-time newsfeeds and ladder systems.

Already released mob titles on the iPhone include SGN’s Mafia: Respect and Retaliation, iMafia, and Mob Wars.

Mafia Wars can currently be downloaded from the iTunes store here. You can also check out the promotional trailer here.