From her myspace page:

Due to unavoidable circumstances I am disappointed and sorry to announce that we have had to postpone NYC,San francisco and Los Angeles concerts until September this year. For anyone who has bought tickets, these tickets will still be valid in September.And I am sorry for any inconvenience.

The good news is that there will be a more extensive U.S and Canadian tour at this time. Thanks for bearing with me! More information to follow....