Specifically, the number of devices that used mobile broadband cellular connections to surf the Web in the fourth quarter of 2007 jumped to 2,168,000, a 154 percent increase compared to the same period the previous year, according comScore, a market research firm.

Users can access mobile broadband networks in several ways: via notebook computers with PC cards, or "aircards;" smartphones or PDAs with built-in adapters; and other gadgets with external adapters. Most current cellular data networks provide slower service than both wired broadband and Wi-Fi connections, which require a different adapter and a "hotspot" within range of the user.

Currently, most mobile broadband users employ PCs to access the Web, and 59 percent of those people are corporate users, comScore says.

Keep in mind, only one percent of the total U.S. Internet population is using mobile broadband today, says Serge Matta, comScore senior vice president. But that will change.

"As consumers increasingly demand and depend on portable Internet access, the demand for mobile broadband should continue to increase," Matta notes, in a release.

Another recent study from research firm In-Stat suggests that the number of smartphones employed throughout the world will increase by an average of 33 percent each year through 2012, and mobile broadband usage can be expected to grow rapidly along with the number of smartphone users.

Last year, U.S. cellular carriers Sprint and Verizon provided the lion's share of mobile broadband connectivity, comScore says, but AT&T, the country's largest carrier by subscribers, plans to ramp up its efforts in the space. AT&T announced this week that it would sink $1 billion into enhancements for its network in 2008.