For completeness and future reference, I should include this link to the Battery Charging v1.2 Spec and Adopters Agreement, USB Implementers Forum

From the USB 2.0 Wikipedia entry for USB 3.0;
Quote:
Several changes and increasing limits including allowing 1.5A on charging ports for unconfigured devices, allowing High Speed communication while having a current up to 1.5A and allowing a maximum current of 5A.