We recently celebrated 25 years of Linux on the 25th anniversary of the famous email Linus sent to announce the start of the Linux project. Going by the same yardstick, today marks the 10th anniversary of the KVM project -- Avi Kivity first announced the project on the 19th Oct, 2006 by this posting on LKML:
The first patchset added support for hardware virtualization on Linux for the Intel CPUs. Support for AMD CPUs followed soon:
KVM was subsequently merged in the upstream kernel on the 10th December 2006 (commit 6aa8b732ca01c3d7a54e93f4d701b8aabbe60fb7). Linux 2.6.20, released on 4 Feb 2007 was the first kernel release to include KVM.
KVM has come a long way in these 10 years. I'm writing a detailed post about some of the history of the KVM project -- stay tuned for that. [Update 3 Nov 2016: I've written that article now at LWN.net: https://lwn.net/Articles/705160/]
Till then, cheers!