In the recent past when trying to add Bluetooth communication to your Arduino project you had to bite the bullet on a seperate and often expensive shield. Armen Kazanchian the founder of California based Open Source RF wants to change this with RFduino.
Built on top of Nordic Semiconductors nRF51822 SoC ('System-on-Chip') and ARM's Cortex M0 processor, this tiny coin sized FCC and CE-compliant micro-computer enables developers and hobbyists to add Bluetooth LE applications to any of your projects making them easily controllable from your smartphone or tablet.
Fully Open Hardware and powered by either a wall outlet, USB, AAA or coin cell battery the device can be extended via an assortment of stackable shields (SD card, relay shield, RGB LED, quad servo controller board, etc are planned).
More details about the kit can be found at Opensourcerf.com or you can watch the Kickstarter pitch video below:
Additional: Kickstater page, EE Times, Mashable, Low Power design