We didn’t ten minutes ago, but we do now. Check out The Verge for more info.
In a move that many have repeatedly hoped for, but have been continuously let down about (until now), Microsoft has declared that upgrading to Windows 10 from Windows 7, Windows 8, or Windows 8.1 (and any equivalent Windows Phone OS versions) will be FREE for one year after release.
I imagine that it will continue to be free after the first year, or at least a remarkably reduced price, but the move should prompt users to upgrade as quickly as possible. That means good news for Microsoft, which will definitely be aggressively promoting the adoption rate for it’s new operating system.