Do you mean like an 802.11b, or g? If so, it's possible. At the CO-OP I worked at, we had access point antennas on top of the grain elevators. We then used 24 dB gain antennas at the customers house (looked like a satelite dish) and we had customers 5 miles (8000 meters) away getting signal. We also had amps on the access point, though.
600 meters, if you use a good antenna, like the 24 dB we had, you should be able to do it. It's also gonna depend on what obstructions are in the way. Trees really messed with the signal. So did power lines.
