Microsoft has announced that Windows 10 will be available from July 29, alongside a free upgrade option for Windows 7 and 8.1 users.
On July 29, you can get Windows 10 for PCs and tablets by taking advantage of the free upgrade offer, or on a new Windows 10 PC from your favorite retailer. If you purchase a new Windows 8.1 device between now and then, the Windows 10 upgrade will be available to you and many retail stores will upgrade your new device for you.
More news at Windows Blog and here at Neowin.