As promised, Sprint has lit up its 4G WiMax service in San Francisco today. “The Bay Area is responsible for creating so much new technology and today we are bringing the power of 4G to our customers in that region who are hungry for fast mobile broadband,” Sprint 4G President Matt Carter said in a press release.

According to the carrier, with the major addition of the Bay Area to its roster, Sprint's WiMAX services are now available in 71 markets across the country.

In other 4G news, it appears that HTC is preparing to unveil its first LTE-enabled device for Verizon, the Thunderbolt 4G. A launch page on the HTC website shows a cloaked device standing among Sprint's HTC EVO 4G, T-Mobile's MyTouch 4G, and T-Mobile's G2 by HTC. The words, "On January 6th, HTC will be the first to 4G. Again," appear across the page. The URL for the preview page has "Thunderbolt-4G" in it.

January 6 lines up quite well with Verizon's promise to unveil LTE devices at CES 2011. Could the Thunderbolt be the same as the HTC Mecha we caught glimpses of in November? Time will tell.