Interestingly, this is actually inspired by "Facebook Zero", which may be the best thing Facebook will do for humanity: inspiring free information access for all.
I think you're talking about free Internet access, which I think only works if the content provider is paying for it himself. Are these Wikipedia SMS's even free to the user?
The standard allows 255 segments of 134 bytes, for ~39000 7-bit characters (GSM 7-bit alphabet) or ~17000 UCS-2 code units.
More seriously – once basic survival needs are met, the next most important thing is education. Life expectancy, living standards, family size and income all correlate highly to education level.
Want to stop HIV/AIDs? You can't do it just by handing out condoms. You need the users to understand why.
E.g. take Africa:
"In its latest quarterly update for the region, the analyst says it expects mobile phone subscriber penetration levels to pass 80 percent in the first quarter of next year." (article from last year):
And/or that technology can't be a benefit in improving access to those even for the people who actually are without clean water or food...
In many of these countries mobiles have become a tool that is massively important in improving market efficiency by disseminating prices - vital in areas where communication is slow and knowing where to take your crop can make dramatic differences in return on investment - accessing information about farming, or the weather, or indeed - as someone else pointed to - to get information about technology that can cheaply help improve their standard of living.
This is being done by the carriers themselves, not the government. And by the way, what makes you think the carriers don't understand their own business? Here's a Wikipedia page to review: http://en.wikipedia.org/wiki/Loss_leader .