As the Senate Commerce Committee prepares to hold hearings tomorrow on the upcoming auction of 700-MHz spectrum, the issue of how to carve up and sell off this extremely valuable slice of airwaves is finally making the leap from the tech press to the mainstream of D.C. politics (though not to the MSM, natch). The latest salvo comes from Sen. John Kerry, who yesterday sent a letter to FCC chairman Kevin Martin calling for a set of rules that will open up the auction to new competitors beyond the cable and telecom incumbents that currently control something like 96% of all broadband access in this country.

"Competition [in America] has been insufficient to drive the innovation that brings faster speeds, next generation applications and a richer, diverse and multifaceted Internet," wrote Kerry. "… We cannot allow this spectrum to be hoarded by large companies who don’t intend to use it, which stifles innovation and the growth of competitive networks."

Kerry thus aligned himself with the 4G Coalition for America (a group of tech heavy hitters that includes Google, Intel, Skype, plus satellite TV companies EchoStar Communications and DirecTV), Frontline Wireless (whose investors include NetScape founder Jim Barksdale, who will testify on Thursday), and a small horde of progressive outfits that includes the Consumer Federation of America, the New America Foundation, and the U.S. Public Interest Research Group in calling for some form of "open access" that will prevent the auction from being dominated by the likes of Verizon and Comcast.

To underline the importance of this auction: The 700-MHz band comprises spectrum being vacated in 2009 by UHF television broadcasters, and these ultrahigh frequencies are extremely powerful for wireless broadband networks because they have a very long range and pass easily through physical barriers like walls. This is almost certainly the last of the great spectrum auctions for a generation, and how this spectrum gets allocated will determine the shape of the broadband wireless industry for years to come.

Many commentators have compared the 700-MHz spectrum opportunity to the FCC's 1968 "Carterfone" decision, which opened up AT&T's monopoly landline network to various devices and helped spark the telecom revolution that eventually led to the Internet.

Now, with something like a quarter-million letters supporting open access flooding in to the FCC, and with Kerry and Democratic presidential candidate John Edwards weighing in, the FCC faces unprecedented public pressure to get the auction right. Among the signs that the incumbents are spooked: The wireless industry organization CTIA has been running ads in favor of the status quo in Communications Daily, the Beltway's favorite telecom trade rag, and CTIA president Steve Largent, a former Republican congressman, has been lobbying Congress and the FCC hard –- apparently with mixed success. With chairman Martin publicly supporting an outcome that favors new competitors, the winds at the FCC are clearly blowing in new directions.

"The days of the free ride for the incumbents like Comcast, T-Mobile, and AT&T are over," opines Wetmachine blogger and open-access advocate Harold Feld. "The day of spectrum public policy — and I mean public in every sense of that word — has arrived."

That may be an overly optimistic assessment, but when big-name politicians start even using the term "700 MHz," it's a good sign that the public debate over nationwide broadband wireless access is shifting.