I'm a backer of the Pebble Time and received this announcement as a Kickstarter project update. In pebble's own words, they call it a smartstrap.
Introducing Pebble smartstraps
We believe your smartwatch should help you accomplish more every day.
When we started Pebble, we opened up the platform and invited the software
developer community to build remarkable experiences for Pebblers everywhere.
Looking at all the amazing things our developers have created over the last 2 years,
we decided to open the platform once more...only this time, for hardware developers.
Have you ever wanted to go for a run without your phone and still track your speed
and distance? How about a Pebble watch with a battery life of more than a week?
What about a NFC chip for payments, keyless car remote, or a pollution sensor?
Rather than trying to shove every sensor and doohickey into the Pebble Time, we decided
to keep the watch simple and functional and give our incredible maker and developer community the opportunity to build from there.
Up until now, if you wanted it all you had to compromise…on battery life, size, design or feature set. Not anymore.
That’s why we created Pebble smartstraps. It’s simple: straps can now contain
electronics and sensors to interface directly with apps running on Pebble Time.