From Lists
The reason BLACKBERRIES are so popular in Africa and became the focus of ire for UK government after last year's London riots was due to people's use of Blackberry Messenger as a free alternative to SMS
here's an explanation of the use of SMS during Ukraine's orange revolution:
here's the link to http://mobileactive.org/ which curates case-studies of mobile reporting during disaster relief, war and activism. and just found this case study http://teesdiary.wordpress.com/2011/04/18/social-media-nigerias-democracy/ about SMS use in Nigeria.