Yeap, looks like it's for real. I'm all for having a siku for mashabiki to celebrate the vitabu and/or JK Rowling, but 7 dakika 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 zaidi Harry Potter related should have been picked to do on the day. I like how mashabiki of Douglas Adams have Towel siku - where mashabiki are encouraged to carry a towel with them on the 25 of May, because according to the Hitchiker vitabu a towel "is about the most massively useful thing an interstellar hitchhiker can have."