Virtualizing the Clock
Dmitry Safonov wanted to implement a namespace for time information. The twisted and bizarre thing about virtual machines is that they get more virtual all the time. There's always some new element of the host system that can be given its own namespace and enter the realm of the virtual machine. But as that process rolls forward, virtual systems have to share aspects of themselves with other virtual systems and the host system itself—for example, the date and time.
Dmitry's idea is that users should be able to set the day and time on their virtual systems, without worrying about other systems being given the same day and time. This is actually useful, beyond the desire to live in the past or future. Being able to set the time in a container is apparently one of the crucial elements of being able to migrate containers from one physical host to another, as Dmitry pointed out in his post.
Read more at Linux Journal