At present, there is the "Festival Musik und Politik", which takes place in late February every year. It is run by a group around Lutz Kirchenwitz and has, I think, a website.

Lutz has published a book on "Folk, Chanson und Liedermacher in der DDR" (Dietz Verlag Berlin 1993) which traces the development of the GDR folk and songwriter scene. Also, there is the 12-CD edition on German folk music by Bear Family Records which has at least two CDs on the GDR scene, with accompanying biographical notes on the artists mentioned. There must be more!