EarthLink and Google quietly announced they have submitted a joint bid to build San Francisco's municipal Wi-Fi network.

EarthLink has a big municipal Wi-Fi contract in Philadelphia and had offered a similar plan to San Francisco last August. Google had proposed a free city-wide network to San Francisco at the same time.

The announcement, made on EarthLink's company Internet blog, said the two had decided to team up to capitalize on a "unique opportunity for both companies." They submitted the joint bid to the city yesterday.

In their bid, EarthLink and Google will "leverage the strengths of both companies," said Donald Berryman, president of EarthLink's municipal networks unit, in a statement posted on the earthlink.net Website. "Fundamentally, this RFP is in line with EarthLink's belief in open access -- that these municipal networks should offer the tools, services and applications that businesses, governments and consumers want to use to enable, enrich and empower their Internet experiences."