Power BI GA date is announced : July 24th , 2015
Details are in our blogs below :
Microsoft blog : http://blogs.microsoft.com/blog/2015/07/10/over-500000-unique-users-from-45000-companies-across-185-countries-helped-shape-the-new-power-bi
PowerBI product group blog: http://blogs.msdn.com/b/powerbi/archive/2015/07/10/announcing-power-bi-general-availability-coming-july-24th.aspx