After spending many hours reading and trying various things.I finally got a working example for i2c bus.
What I did:
1.Configured the kernel for I2C support
-in /home/giannis/gumstix-buildroot/build_arm_nofpu/linux-2.6.11gum
make -j3 -C /home/giannis/gumstix-buildroot/build_arm_nofpu/linux-2.6.11gum ARCH=arm CROSS_COMPILE=/home/giannis/gumstix-buildroot/build_arm_nofpu/staging_dir/bin/arm-linux-uclibc- menuconfig