"The chip pictured has the part number BMP282. I'm 99.99% sure this is a Bosch barometric pressure sensor, similar to this part BMP280. Variants of one part often have slightly different part numbers- if Apple got Bosch to customize the chip for them with different packaging, or a slightly different measurement range, that would explain the difference in part number."
Barometric pressure sensors can be used for GPS and indoor/outdoor navigation enhancement, weather forecasting, altimetry, and spirometry, the lung function measurements that were added to Apple's Health app in a recent iOS 8 beta.
Another post on the same thread by kdarling corroborates leecbaker's conclusions, "Yep, that chip's pins also match the schematic" and notes that the BMP series unfortunately does not have humidity and temperature sensing capabilities. "Too bad the chip has a BMP prefix, and not BME. The latter also includes humidity and temperature sensors."
Check out the schematic below!
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