Interestingly, at the same time that the cartels (the Zetas in particular?) are killing bloggers, Startfor reports that on September 8 the Mexican navy dismantled the Zetas’ communication network in Veracruz (link by subscription only).
On the massive raid, the navy seized seven trailers that served as base stations, along with computers, encryption devices, solar cells, and other equipment.
Los Zetas have more sophisticated networks than most cartels due to their origins with the military, and they use their knowledge (and massive proceeds from the drug trade) to avoid regular cell phones and other devices that are easily monitored.
The location of the raid, Veracruz, makes it tactically valuable, for its vicinity to population-dense Mexico City and its financial institutions.