Google has revealed plans for a WiFi network.

So far, Google has set up two free beta hotspots for WiFi users near its Mountain View, California headquarters. Supposedly, only at these locations can users currently download Google’s new security software, which encrypts network traffic and routes it through Google VPN gateways.

One possible long-term opportunity that Google-watchers are speculating about is mobile telephony. WiFi networks could become even more valuable with the advent of dual-mode mobile phones, which have both cellular and WiFi network capabilities. Dual-mode phones resolve spotty coverage problems and the need to blanket an area with large base stations by transparently switching between both types of networks.

Whether the search company decides to spend its billions on building an expanse of WiFi networks to become a full-fledged cellular carrier, or sell out to or partner with a cellular carrier is anyone’s guess. But what does seem certain is that Google will expand and deploy a larger WiFi network.

Of course, Google’s WiFi hotspots would also be synergistic with its online search business. WiFi users using Google’s public access points may default to Google’s home page, boosting user and advertising numbers. In turn, this would help solidify its position in the search market against rivals hungry for a larger slice, such as Microsoft.

There also has been a lot of noise lately about Google acquiring vast amounts of dark fiber, or unused fiber optic cable. There has been speculation that Google may be buying these lines to lay a foundation for a national wireless Internet network.

But its core online-search business relies on this kind of infrastructure, which is important for interconnect and the backhaul of data between its server centers, and this behavior by Google could also simply be business as usual.