"There's relatively little risk [to taxpayers], because in that model, the city doesn't spend any money," Vos said. "They put out public tender and ask somebody to bear the cost." Providing access to city-owned assets like utility poles is necessary to keep the price down, Vos said.

In addition to selling access, EarthLink also must keep the network open so that other providers can sell access. That makes EarthLink both a wholesaler and retailer of access services. That helps EarthLink, and it helps ensure a competitive atmosphere for connectivity, Vos noted.

Balhoff says that despite appearances, there is risk to taxpayers.

"If it's so attractive for EarthLink to absorb the entire risk, why wouldn't they go in there without the headache of aligning themselves with the city of Philadelphia?" he asked. "Instead, it gets a partial endorsement from the city, and there are financial advantages that will accrue to EarthLink that, in effect, use taxpayer dollars and potentially create conflict of interest."

One concern should be what will happen if entities like EarthLink don't make enough money, Balhoff said. He stressed that the subscriber projections he has heard for Philadelphia are overly aggressive, and if subscription numbers aren't met, EarthLink's commitment could waver.