I read this article yesterday about the radio station (or actually radio program) that has recently opened in April 2007 that are run by North Korean defectors who now are living South Korea. The main argument of the article was that in May/June after about a month of running the program, eviently there was some complaint from North Korea to stop the program though article didn't mentioned specifically about the details of the complaint - but it was certain that North Korea didn't like this new radio station.
Anyhow, while searching for the similar story about this new radio station, I actually found the translated version of the article written by Korean Herald that expalins not only about the radio station but also how it was created and about this political group formed by North Korean defectors, thought that it will be interesting read. The article mentioned that there are "various views of over 100,000 North Koreans who have defected to the South", I honestly didn't know that there were so many North Korean defectors in the South - my estimate was about 10,000 at most but guess not.
Anyways, here is the link to the article "N.K. defectors form new political group"