According to the INEGI the homicide rate was 24 and the total number of homicides in 2011 was 27,199.
Homicides actually went down in many of the most violent states in 2010. Chihuahua, Sinaloa, Baja California and Sonora all registered a drop in homicides in 2011, though they still are way above their longtime trendlines. In Chihuahua and Baja California it's been claimed that part of the reason for the drop in homicides is the fact that the Sinaloa Cartel won control of the plaza (the drug smuggling routes and the political and law enforcement arrangements through which drug traffickers work). Since the Mexican government seems to be going after the Zetas rather than Sinaloa there seems to be one hell of an incentive to invade other cartel's plazas.
Deaths of unknown intent and by homicide in San Luis Potosí