Read a Wired article about MIT's Fab Lab project, which illustrates one of the ways I think Open Source ideology can help third-world nations.
The Fab Lab is an effort to create a small lab/machine shop which can fabricate just about anything, allowing an area to jump-start its economy by manufacturing the things it needs rather than importing them. Currently the whole lab runs on open-source software, and one of the lab's stated goals is eventually to use all open-source hardware designs -- one of the prerequisites for a self-replicating lab.
I'm interested to see where this project goes. Like many MIT projects, it's pretty long-ranged. I'm most interested to see how they tackle computer chip fab -- while PCBs are relatively easy to make in small quantities, the making computer chips themselves is off-limits to everyone but a fairly small group of companies. Does the lab have some way in mind to do inexpensive low-volume chip production?