On several occasions, governments have shut down communications systems to prevent people from organizing protests and/or reporting on malicious governmental activity.
Thoughtcrime creates a mesh network that allows an iPhone to share its cellular or WiFi connection to neighboring iPhones using bluetooth and/or adhoc WiFi. Then, all of those iPhones will be able to share that initial phone's internet connection with their neighbors, and so on. This allows one person with an internet connection to spread that internet connection (essentially, through a system of repeaters) to other devices that may not be in range of the original network.
Thoughtcrime makes it such that, when communications are shut down in an area, a group of phones themselves can act as repeaters from a source outside said area. This is not very high-performance, but could be enough to get Tweets in and out.
Q: Why the name "Thoughtcrime"? A: "In George Orwell's dystopian novel Nineteen Eighty-Four the government attempts to control not only the speech and actions, but also the thoughts of its subjects, labelling unapproved thoughts with the term thoughtcrime"