Google is providing a free WiFi network under "GoogleWifi" (802.11b/g) in Mountain View, CA. Anyone can use it, including business, visitors and the 72,000+ residents. You must sign into the network with your Google Account, it is not fully public in that sense, but anyone can register for access. Ready to get started using GoogleWifi? There are more details on the "how to" at http://wifi.google.com/support and at the Google Blog.
I believe this is the first of many cities that Google will be providing free Wifi access to.
Postscript: The New York Times reports that "Google Says It Has No Plans for National Wi-Fi Service," I still believe they will continue to expand their network. Heck, cell phone coverage isn't completely nationwide, so how would we expect WiFi coverage (especially free coverage) to span the nation completely?