The funny part is that more of the world population has access to Facebook than to safe drinking water. EVERYONE's got a mobile phone with internet these days. Even the people who don't even get water or access to banks for that matter.
For instance, in a lot of Africa mobile operators have filled in for the role of credit cards and things like that. People pay for everything via sms.
My experience of Africa (Mozambique) was that they have the phones but don't pay for anything because they have no money. Technically possible, sure, but most people only had credit for a limited amount of time (and would use it for sending messages to communicate). You had to be seen to have a phone (which were probably free).
In Kenya, for instance, 68% of phone users make/receive payments on their phone. And 76% of them use their phones for social networking. At the same time, 82% of Kenyans have a mobile phone. But only 59% have access to clean water. -> http://water.org/country/kenya/
So that's .82*.76 = 62% of Kenyans with social networking vs. only 59% with clean water.
At the time, 93% of South Africans had access to clean water and mobile penetration was at over 100%.
For the whole of Africa, it was ~46% water to 50% phones.
But, as ever, definitions are important. If you have to spend half a day walking to a well for a bucket of water - that counts as access. Similarly, a family who shares a phone each has "access".
It's also a lot easier to build a mobile phone network than a water network. Stick up a tower, power it with a generator / solar power, and point it to a back-haul link. Hey presto, you've got wide area coverage.
I'm surprised it didn't catch on sooner. It's a genius idea for enabling online payments in places where credit cards, PayPal etc. aren't as commonplace as they could be.
For instance, in a lot of Africa mobile operators have filled in for the role of credit cards and things like that. People pay for everything via sms.