Set your Clocks! Check out www.coldplay.com tomorrow, April 29, after 7:15 a.m. for details on how to win tickets to Coldplay’s June 23 show at Madison Square Garden. Tickets are free, but you gotta win ’em. While you’re there, you can also download their first single, “Violet Hill,” from their upcoming, Brian Eno-produced album, Viva La Vida. The album will be officially released on June 17.