There is no concert and the only music heard will be the tinny sound of portable speakers blaring Michael Jackson’s greatest hits. But event organizers expect thousands of the singer’s fans to converge on the O2 Arena in London Monday to mark what would have been the opening night of the singer’s long-awaited comeback, the first in a grueling 50-date “This Is It” concert tour. They will be bringing candles, flowers and photos for an impromptu memorial service organized over social networking sites including Facebook
