Coming in just a hair under its self-imposed deadline, Sprint is set to launch its WiMAX network in San Francisco and the surrounding area next week. Beginning December 28th, subscribers with WiMAX-enabled devices like the Sprint Overdrive and HTC EVO 4G will have access to Sprint’s 4G network in San Francisco, Oakland, San Jose, Silicon Valley and other Bay Area cities. Sprint currently offers a $60 monthly plan for unlimited WiMAX service alongside its 4G laptop dongles or its Overdrive portable hotspot. Sprint’s 4G service is also available as part of a $10 enhanced data add-on with compatible smartphones.