No, we're not talking about the white space that you see on such websites as Google+, but unused mobile spectrum. According to The Telegraph, Google and Microsoft are competing over access to these "white spaces" in the UK.
Even though 3G and even some 4G access is available in the UK to customers, some people opt for using WiFi instead. What these white spaces could be used for is WiFi connectivity and would boost the amount of connectivity one would could have on the go.
Of course, the speculation is that users would have free access to this WiFi, but nothing has been confirmed as of yet. It's an interesting concept and being that Google or Microsoft could get access to it, would mean that carriers couldn't touch it and the possibility of it being free much more likely.
For example, rural users would get access to it being that it has more range than traditional WiFi, and companies could offer it for free in exchange for displaying of ads. Currently, these spectrums are virtually dead with no use.
Ofcom, the telecommunications regulator in the UK, wants these "white spaces" to be used more efficiently which is where Microsoft or Google could come in and finally make great use. Don't expect to see anything anytime soon, but if the reports are correct, there could be some exciting news for those in the UK.