The term “high speed” might mean something different from now on, with Telstra’s unveiling of the first wireless broadband device capable of hitting downlink speeds of 42Mbps. The device, which plugs into your computer through a USB port, should deliver speeds higher than that of many ADSL2+ providers.

While some broadband providers cap out at 20Mbps, Telstra’s upgrades to the NextG network allow for a higher maximum speed, thanks to the use of HSPA+ Dual Carrier technology. With Dual Carrier, the download speed is effectively doubled through the use of two connections. The speeds on offer are twice that of regular mobile 3G connections, though actual download speeds are unlikely to reach the full 42Mbps.

Telstra's first device to take advantage of this new technology is made by Sierra Wireless.

Telstra’s first device to take advantage of this new high speed technology is manufactured Sierra Wireless and slated to arrive later this year. Prices aren’t yet known, but you can expect that a fast new technology like this will be more than a pocketful of pennies, either as a standalone purchase or on a plan.

You probably won’t be replacing your home connection with the HSPA+ dual carrier technology, but if you need the best speed when you’re out in the field, HSPA+ will be the fastest game in town.

It’s worth noting however that there’s more around the corner for high speed broadband. HSPA+ Dual Carrier looks to get an upgrade in 2011 that will double the speed of the 42Mbps announcement to 84Mbps. You will likely need a new modem to support these speeds.