Google’s Nexus One is now available in a version that will run on AT&T’s 3G network. The new model can be purchased as an unlocked device without a service plan.

In addition to AT&T’s 3G network, the device will also run on Rogers Wireless in Canada. And like the first version of the Nexus One, it can be used with most GSM operators globally.

AT&T does not plan to subsidize the Nexus One in exchange for agreement to a two-year contract from customers. Nexus One devices can now be shipped to Canada from Google’s Web store and will work with a SIM from Rogers Wireless.

When the Nexus One first rolled out, it was compatible with T-Mobile’s 3G network in the United States but featured only limited 2G or EDGE compatibility with AT&T. That was mainly due to the fact that T-Mobile and AT&T, while both GSM networks, run on different frequencies.

The AT&T version of the Nexus One supports three 3G/UMTS bands (850/1900/2100 MHz) and four GSM radio frequencies (850/900/1800/1900 MHz). The T-Mobile version supports three 3G/UMTS bands (900/AWS/2100 MHz) and four GSM radio frequencies (850/900/1800/1900 MHz).

The unlocked version of the phone retails only on Google’s online outlet for $529. The subsidized version of the phone through T-Mobile runs $179.