USB 3.0 Overview

The Universal Serial Bus or well known as USB was introduced to the PC world in 1996 which dramatically simplify the connection between host computer and peripheral devices such as mice and keyboards, external hard drive or optical devices, Bluetooth and many more peripheral devices in the market.
Let's take a quick look on the USB evolution referencing to the table below. 
 

USB 3.0 aka. Super Speed USB

For years, the USB 2.0 has been firmly entrenched as the de facto interface standard in the PC world with about 6 billion devices sold, and yet still the need for more speed grows by ever faster computing hardware and ever greater bandwidth demands. The USB 3.0 finally has the answer to the consumers demands with a theoretically 10 times more faster than it's predecessor. In a nutshell, USB 3.0 features are as the following:

• Higher transfer rates (up to 4.8 Gbps)
• Increased maximum bus power and increased device current draw to better accommodate power-hungry devices
• New power management features
• Full-duplex data transfers and support for new transfer types

How does USB 3.0 achieve the extra performance?

USB 3.0 achieves the much higher performance by way of a number of technical changes. Reference to the picture below, perhaps the most obvious change is an additional physical bus that is added in parallel with the existing USB 2.0 bus. This means that where USB 2.0 previously had 4 wires (power, ground, and a pair for differential data), USB 3.0 adds 4 more for two pairs of differential signals (receive and transmit) for a combined total of 8 connections in the connectors and cabling. These extra two pairs were necessary to support the Super Speed USB target bandwidth requirements, because the two wire differential signals of USB 2.0 were not enough.

Furthermore, the signaling method, while still host-directed, is now asynchronous instead of polling. USB 3.0 utilizes a bi-directional data interface rather than USB 2.0's half-duplex arrangement, where data can only flow in one direction at a time.

Will the existing peripherals still work? How will they co-exist?

The good news is that USB 3.0 has been carefully planned from the start to peacefully co-exist with USB 2.0. First of all, while USB 3.0 specifies new physical connections and thus new cables to take advantage of the higher speed capability of the new protocol, the connector itself remains the same rectangular shape with the four USB 2.0 contacts in the exact same location as before. Five new connections to carry receive and transmitted data independently are present on USB 3.0 cables and only come into contact when connected to a proper Super Speed USB connection.

What operating systems support USB 3.0?

Microsoft announced that Windows 7 would have USB 3.0 support, perhaps not on its immediate release, but in a subsequent Service Pack or update. It is not out of the question to think that following a successful release of USB 3.0 support in Windows 7, Super Speed support would trickle down to Vista. Microsoft has confirmed this by stating that most of their partners share the opinion that Vista should also support USB 3.0.
Super Speed support for Windows XP is unknown at this point. Given that XP is a seven year old operating system, the likelihood of this happening is remote.

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