The official launch event of Windows 7 is still hours away, but the latest iteration of the Windows client from Microsoft has already hit the market, as initially scheduled, today October 22nd, 2009. The successor of Windows Vista is now available for purchase for customers in markets around the world, while Microsoft is gearing up for the official release in the U.S. The Redmond company has already confirmed that the main event celebrating Windows 7’s General Availability will be hosted in New York City and will feature its Chief Executive Officer Steve Ballmer.

The software giant had planned to release Windows 7 three years after the General Availability of Windows Vista, namely before January 31, 2010. With the October 22nd launch, the company has beat its own estimates by three months, staying true to the “underpromise and overachieve” strategy that marked the entire development process of Windows 7.

As far as Windows 7 testers and early adopters go, Microsoft offered the first taste of the operating system a year ago at the Professional Developer Conference 2008 in Los Angeles. At that time devs got to play around with an API-complete (application programming interface) Windows 7 Milestone 3. Microsoft made sure to cut the functionality associated with Windows 7 out of the M3 build, so it made the release look more like Vista, just as M1 and M2 had been.

In January 2009, at the Consumer Electronics Show, Windows 7 debuted into Beta development stage. Build 7000 was feature-complete even at that time, with a few exceptions including Windows Virtual PC and Windows XP Mode. It was in May 2009 that Microsoft made available for download the second major testing build for Windows 7, namely Release Candidate version 71000. The company wrapped up Windows 7 on July 22nd and released the operating system to manufacturing. OEM’s were the first to get the gold bits of Windows 7, with MSDN and TechNet subscribers second, followed by Volume License customers, students, system builders and last, general consumers. All in all, Windows 7 was test driven by in excess of eight million people, making this the broadest Beta in company history.

I’m only just starting the Windows 7 General Availability coverage. Make sure to keep an eye on Softpedia for more Windows 7. Read the Windows 7 Softpedia Review here.