I use Eclipse with the AVR plugin and get the following linker error. It would seem that the included source is not compiled. Like the libraries for instance.
Invoking: AVR C++ Linker
avr-g++ -Wl,-Map,HLS.map,--cref -Wl,--gc-sections -L"C:\Users\Marius\Arduino\ArduinoCore\Release" -mmcu=atmega328p -o"HLS.elf" ./AT25DF.o ./BMP085.o ./Battery.o ./Beeper.o ./Datastore.o ./Firmware.o ./Messages.o ./Radio.o ./SPI.o ./Settings.o -lArduinoCore
./BMP085.o: In function `BMP085::setup()':
../BMP085.cpp:47: undefined reference to `Wire'