What operating systems support USB 3.0?
Apple Mountain Lion (10.8) and Microsoft Windows 8 - both shipping in 2012 - came with native USB 3.0 support whereas third party drivers for Windows 7, Vista and XP have been availablesince 2008.
Apple has remained silent on the issue of USB 3.0 support in Mac OS X even when the public knows well that Macs will eventually get Ivy Bridge (Intel third-gen Core i CPUs) whose Panther Point platform comes with USB 3.0, for free. For a while, there was an ongoing debate over whether or not Apple will adopt USB 3.0 given its enthusiasm for Thunderbolt. But in mid-June 2012 at WWDC, Apple finally introduced USB 3.0 to its entire line of MacBook Air and MacBook Pro as part of Ivy Bridge processor refresh and at the same time, OS X Mountain Lion (10.8) was announced to ship in the following month. So, USB 3.0 support on Macs officially begins with Mountain Lion.
LaCie and HighPoint have developed their own USB 3.0 driver for Mac to work with Mac OS X from Leopard (10.5). LaCie solution however only works with its own drives, including FastKey SSD, 2big RAID, Rikiki portable drive.
In October 2012, Microsoft started shipping Windows 8 with built-in USB 3.0 support. The Windows team said it has written completely new software stack for USB 3.0 rather than adding support on top of the current USB 1.1/2.0 drivers. To save time, work on USB 3.0 software stack actually began way before there were any peripherals so the engineers had to come up with something called virtual USB 3.0 devices for simulations. In retrospect, the team probably has plenty of time since USB 3.0 wasn't an instant hit and was slow to take off.
Built-in support for USB Attached SCSI Protocol (UASP) will come as well. This will supplement Bulk-Only Transport (BOT) which has its roots in USB 1.1. USAP class driver, which benefits mass storage applications, adds command queuing to deal with multiple concurrent requests and offers lower overheads than BOT protocol. In other words, you will see even faster transfer rate and lower CPU usage. Only a handful of USB 3.0 drives support USAP as of this writing but on Windows 8, USAP mode will only kick in when the drive interfaces with a USB 3.0 host controller that conforms to xHCI 1.0 specification.
Windows 7, Vista & XP
Intel, Renesas and other fabs have been updating their own stable USB 3.0 software stacks for Windows 7, Vista and XP in the last several years. So there's no reason for us to believe Redmond is in any hurry to bring USB 3.0 support via service packs to the aforementioned Windows platforms.