Looks like somebody has jumped the gun at Ticketmaster and listed one of the 2010 North American dates for the 360° Tour early. Currently, this page
shows that U2 will be playing at Land Shark Stadium in Miami, Florida on 9 July 2010.
As the page may be removed at any time to await the official announcement of the 3rd leg of the tour, I'll reproduce here the ticketing information it gives.
Ticket prices are specified as ranging from $30 to $250. No more precise details are provided.
The public ticket sale time is given as 9 November 2009, starting at 10am. This is to be preceded by two presales, for U2.com and Miami Dolphins members. The same time period is given for both of these presales: 10am Tuesday 3 November to 5pm Thursday 5 November.
The announcement of the 2010 North American leg is evidently imminent. Stay tuned ...Update:
Ticketmaster have evidently noticed their mistake and taken the page down. However, thanks to atu2.com, you can view a screenshot of it here