AMD has a 1000Mhz HyperTransport Bus (200MHz HTT x 5 LDT Multiplier). However, AMD can send two instructions per clock cycle on it's HT Bus, similar to how DDR (Double Data Rate) RAM functions. So, the effective Bus speed on a Socket 939 AMD system is 2000MHz. Some websites will advertise it as 1000MHz, while others will call it 2000Mhz, the same as how some sites will classify DDR400 RAM as running at 200MHz, while others will classify it as 400MHz.
For future use, the correct way of saying it is the "actual" speed as opposed to the "effective" speed. However, one can be excused for making such an error.