Three full weeks before T-Mobile’s Google-powered G1 handset is due to arrive, the wireless carrier has lit up its high-speed wireless spectrum in San Francisco. The UMTS/HSDPA service is usable on handsets that currently support the 1.7 GHz frequency like the upcoming G1 and the currently available Sony Ericsson TM506, allowing their owners to take advantage of a network not yet oversaturated by data-hungry devices.

San Francisco was on a short list of cities slated to receive the faster network by mid-October. Over the next few weeks, it’s due to be followed by Atlanta, Chicago, Los Angeles, Orlando, Seattle and California’s state capital of Sacramento. Since the recently launched Google Android handset heavily leverages a high-speed data connection and Google has such a looming presence in the area, it’s fitting that T-Mobile light up the network there sooner rather than later.

T-Mobile will need to sell quite a few devices capable of using the network to see a solid return on their investment. Or rather, they’ll need customer commitments to long-term data plans that build a revenue stream, as the 3G investment in San Francisco alone cost over $322 million to implement. The G1 handset can actually help sell the network, but much will depend on whether or not developers embrace the platform and deliver a wide array of applications for the network-centric device.