Adafruit has a great guide on getting started with WS2812B LEDs/NeoPixels @ https://learn.adafruit.com/adafruit-neopixel-uberguide
NeoPixels run on 5V and the Particle Photon runs at 3.3V, so we might need to pick up a a logic level shifter such as a 74AHCT125 or a 74HCT245.
The Uberguide states that, "If you are powering your NeoPixels with 3.7v like from a LiPoly, a 3.3v data signal is OK." This might also be true for the Photon--or maybe is true for the Photon running a few NeoPixels.
There's a ton of exciting choices with the NeoPixels and I'm working on figuring out which NeoPixels to pick up. Let me know your suggestions :)