Lately my BMP085 temperature sensor, connected to a Raspberry Pi through the i2c interface stopped working.
Turns out that all I needed to do was apt-get install raspi-config, and use that raspi-config tool to enable i2c.
Great.
Btw, if you have difficulties to keep the i2c device up at reboot, create this file:
/etc/udev/rules.d/99-i2c.rules
Add this line:
SUBSYSTEM==”i2c-dev”, MODE=”0666″