In a post announcing plans to play the Glastonbury festival in 2011, U2.com also inadvertently revealed a possible date with Charm City June 22.
Representatives for M&T Bank Stadium and tour promoters Live Nation have not returned calls for comment.
It's not the first time the band has teased Baltimore with a possible performance.
Last year, Ravens president Dick Cass told Midnight Sun the stadium almost booked the band for a date, but it conflicted with the game schedule.
But if the 2011 date works, it would be the first major league non-sports event at the stadium in recent years, and the biggest headliner in the area since Bruce Springsteen played
M&T Stadium 1st Mariner last year.
Baltimore radio stations reported the 2011 rumor earlier this week. But it wasn't any more than wishful thinking until the post went up Oct. 2.
A picture from the band's accidental post, after the jump.
U2 fan site atu2.com grabbed this screen shot from the band's official website before it was taken down: