Coming soon to a driveway near you

And timekeeping just gets more and more accurate - from Physics World:

Optical clocks hit the road
Two independent groups of physicists in Germany and China have built portable optical clocks that are more accurate than the best caesium devices. They say that their instruments could be used to compare the timekeeping of different optical clocks distributed across the globe, and so take us closer to an overhaul of the SI definition of the second. They also reckon their compact clocks could be used by geodesists to determine the height difference between two widely spaced points on the Earth's surface.

All atomic clocks rely on counting the oscillations of an electromagnetic wave with a frequency that is locked to that of a known atomic transition. Traditional atomic clocks use a microwave transition in caesium-133 to fix the output of a crystal oscillator, whereas optical clocks use much higher optical frequencies generated when a monochromatic laser beam interacts with various species of trapped ions or with clouds of cold atoms. These clocks now have accuracies and stabilities that are nearly two orders of magnitude higher than those of the best caesium devices – at levels of a few parts in 10¹⁸ rather than 1 part in 10¹⁶.

Very cool - I have a very accurate clock here but it is only good to 10¹³ - still a couple thousand times better than your household clock or good watch. Accurate to one second in two hundred years.