If memory serves, this is Mew’s first ever show in Poland. OFF Festival 2010 will take place in the city of Katowice in Dolina Trzech Stawów (Three Lake Valley). The festival is held on August 5th through August 8th, but we have no exact date for Mew yet. Still, it will be on one of the festival’s first three days, because Mew will play in Skanderborg, Denmark on August 8th.
EDIT: Mew announced the exact date, it’s August 7th.