Apple has stopped selling Fitbit devices in the Apple Online Store. The move comes after a report last month that Apple would remove Fitbit products from retail locations. No word yet on if Fitbit products have been removed from Apple's physical retail locations.
Previously under the Fitness & Sport section, Fitbit's devices are nowhere to be found. The Store is still selling rival products like Jawbone's UP24, the Withings Pulse, and the Nike+ Fuelband SE. No formal announcement of the removal was made, and no reason has been given. It's possible that it is related to Fitbit's decision to forego HealthKit integration for the time being.
Source: Apple Online Store