Yeap, looks like it's for real. I'm all for having a ngày for những người hâm mộ to celebrate the sách and/or JK Rowling, but 7 phút of silence?!! I agree with cassie-1-2-3's link on that one: it's disrespectful towards real victims of tragedies and wars.
Something a bit thêm Harry Potter related should have been picked to do on the day. I like how những người hâm mộ of Douglas Adams have Towel ngày - where những người hâm mộ are encouraged to carry a towel with them on the 25 of May, because according to the Hitchiker sách a towel "is about the most massively useful thing an interstellar hitchhiker can have."