Atomic clocks the size of rice grains?

[Napier]

A few years ago researcheres announced a grain-sized atomic clock oscillator, saying it would soon have a huge impact on handheld GPS, precision watches, communication gear, and other devices.

What’s new on this story?

Also, I see that rubidium frequency standards selling new as low as around $900 to $1500 are perhaps the low end on atomic clocks these days - are there any cheaper?

[Nametag]

Choice quotes from Wikipedia:

In August 2004, NIST scientists demonstrated a chip-scaled atomic clock. According to the researchers, the clock was believed to be one hundredth the size of any other. It was also claimed that it requires just 75 mW, making it suitable for battery-driven applications. This device could conceivably become a consumer product. It will presumably be much smaller, consume less power, and much cheaper to produce than the traditional cesium-fountain clocks used by NIST and USNO as reference clocks. It is uncertain if it will become a consumer product.

The lifetime of a standard is an important practical issue. Modern Rubidium standard tubes last more than ten years, and can cost as little as US$50. Cesium reference tubes suitable for national standards currently last about seven years and cost about US$35,000. The long-term stability of hydrogen maser standards decreases because of changes in the cavity’s properties over time.

I’ve checked out NIST’s page on the micro-clock, and Wiki appears to be correct.