Up to 1600 Korean students are suspected of cheating by sharing answers using mobile text messaging in the recent CSAT (equivalent of SAT in the US) exam.
The nationwide investigation started with uncovering of a highly organized ring of high school students. The ring had been in operation for a few years and not all of the students were of exam-taking grade. Older students directed the operation with possible monetary rewards as incentives and younger students helped out as answer distributors.
With high price for failure, cheating in exams is nothing new in Korea, with private sessions by teachers and impersonation by college students being more popular way to cheat. It's ironic that Korean students ranked first in problem solving (Liechtenstein?) according to a recent survey.
The investigation widened when the police mined the archive of SMS messages sent during examination and found that a simple string search with sequence of numbers representing answers to multiple choice questions turned up hundreds of suspected text messages. This sparked concerns for privacy as well, so Korean mobile providers say that SMS messages will no longer be archived. I don't quite trust them to do that though.