When: May 2011
Tentative Lineup: DBSK, Super Junior, SNSD, Shinee, BIGBANG, 2NE1, Beast, 2AM, IU, Jay Park, F(x), Mblaq, 4Minute, After School, KARA, CNBlue.

Line-up still subject to change. Schedule and more details will be announced soon on Gmarket (http://www.gmarket.co.kr/). Stay tuned ;]

Source: DC2011 Twitter
Via BBupdates