Mason Inman explains in an article in the MIT Technology Review:
Internet access is growing steadily in developing nations, but limited infrastructure means that at times connections can still be painfully slow. A major bottleneck for these countries is the need to force a lot of traffic through international links, which typically have relatively low bandwidth.
Now computer scientists in Pakistan are building a system to boost download speeds in the developing world by letting people effectively share their bandwidth. Software chops up popular pages and media files, allowing users to grab them from each other, building a grassroots Internet cache.
Sounds like a good system (the article goes into detail about how it works) and here's hoping it's a great success.