We knew since a little earlier this month, that Microsoft's next major operating system's launch is scheduled for October, with enterprise/partner availability in August. The Windows Team let out a specific date for availability to consumers: Fri., October 26, 2012. The date was announced by Steven Sinofsky, president of Windows division at Microsoft, at the company's annual sales meeting. The Friday launch allows users to spend the weekend with installations and getting a hang of the new OS.
Source: Windows Team Blog