Interestingly, the Developer Notes for the MacBook Pro are different for the current and previous generation models; I'm not sure why, other than maybe the Santa Rosa chipset in the current model is actually more capable in the USB department. The System Profiler on my 10/2006 MacBook Pro indicates that the USB bus power for each port (left and right) is
500mA.
From the Developer Notes:
*15-inch MacBook Pro Computer (June 2007)*
The 15-inch MacBook Pro computer introduced in June 2007, based on the Intel Core 2 Duo, has an internal USB 2.0 controller built into the South Bridge with one Enhanced Host Controller Interface (EHCI) and four Universal Host Controller Interfaces (UHCI). The controller has a total of eight ports, five of which are available to support two external USB ports, the Bluetooth module, the IR receiver, and the built-in iSight camera. The other three ports are used for the internal keyboard/trackpad, the ExpressCard/34 interface, and one is not used.
+*The eight USB ports comply with the Universal Serial Bus Specification 2.0. The USB register set complies with the EHCI and UHCI specifications.*+
+*The USB ports support 500 mA at 5 V nominal for 2.5 W power per port and are compliant with the the Voltage Drop Budget section of the Universal Serial Bus Specification 2.0.*+
*15-inch MacBook Pro (October 2006)*
The 15-inch MacBook Pro computer introduced in October 2006, based on the Intel Core 2 Duo, has an internal USB 2.0 controller built into the South Bridge with one Enhanced Host Controller Interface (EHCI) and four Universal Host Controller Interfaces (UHCI). The controller has a total of eight ports, five of which are available to support two external USB ports, the Bluetooth module, the IR receiver, and the built-in iSight camera. The other three ports are used for the internal keyboard/trackpad, the ExpressCard/34 interface, and one is not used.
+*The eight USB ports comply with the Universal Serial Bus Specification 2.0. The USB register set complies with the EHCI and UHCI specifications.*+
From
http://developer.apple.com/documentation/HardwareDrivers/Conceptual/HWTechUSB/index.html#//appleref/doc/uid/TP40003026 and
http://developer.apple.com/documentation/HardwareDrivers/Conceptual/15inMacBookP ro_0610/index.html .