There seems to be a growing interest in mobile broadband hotspots, in the operator community at least, which may seem a little strange given the recent noise about femtocells and moving traffic off the macro network.

But some carriers seem intent on using wifi-enabled devices to shift traffic on to the macro network. The latest to join in this game is US provider Sprint, which on Wednesday unveiled a 3G/4G mobile broadband hotspot made by Sierra Wireless.

The Overdrive allows up to five wifi devices to be connected at any one time and backhauls the connection over Sprint/Clearwire’s WiMAX network, defaulting to the provider’s EV-DO network when out of WiMAX coverage.

The WiMAX connectivity is the selling point in this case and Sprint’s not shy about telling users what they can do with that bandwidth referencing such connection intensive applications as HD movie streaming, mobile TV, music streaming and gaming.

The Overdrive will be available from January 10 for $99.99 after a $50 mail-in-rebate with a two-year service agreement.

The Overdrive is similar in concept to the MiFi, manufactured by Novatel, which is a pocket sized box powered by batteries or a mains supply and can connect up to five wifi-enabled devices with a cellular backhaul connection – a sort of 3G dongle on steroids.

Telecoms.com has been playing with one of the Novatel devices and is impressed by the concept, which is more user friendly than a dongle because, with  no software to install, everything is accessed via a web interface. But the main benefit is that you can move the unit to an optimum coverage position — by the window, say — and leave your laptop or other wifi-capable devices on the desk or a more comfortable location.