Google's call to free intra-band spectrum for WiFi use may belie their strategy in the recent spectrum auctions in the US when they clearly bottled their bids.
Now, there's a tradition of this in television, starting with the BBC engineers who used spare spectrum in the broadcast signal to add a teletext service. If you want to see how US spectrum is currently allocated, check out this chart.
One solution is the use of Cognitive Radio. This involves using bandwidth switching to make maximum use of unused spectrum allocated for existing, especially analogue services.
But there are powerful organisations that want bandwidth to be a rarity, including the ones who have recently paid a significant amount of money for government sanctioned usage. Google may be being naive, or they may be playing a cleverer game..