Even today, with up to a thousand trekkers camped along the track each night in peak season, there is not a single route from what is now known as Owers Corner in the south to the Kokoda Valley in the north, but alternative tracks that go through different valleys and different villages for about 98 kilometres.
The track became famous during the Second World War when troops of the 39th Australian Infantry Battalion [http://en.wikipedia.org/wiki/Kokoda_Track_campaign] and Japanese Imperial Forces fought a long and arduous battle along its route to prevent the Japanese forces from reaching Port Moresby in the south.
Since then, and particularly in the past two decades, walking the Kokoda Track has become a rite of passage for Australians of all ages, on a par with visiting Gallipoli on Anzac Day. However, trek parties of more than 100 trekkers and guides mean the track is no longer the isolated place it once was.
Certainly it is difficult for Australians and Japanese to not shed a few tears when they reach the war memorial site at Isurava.
The second thing is the importance of a decent water purifying system; iodine pills work great but they taste awful so think about complementing that with water purification tablets to take away the taste. Sometimes it might be far between the streams to refill your bottles so be sure to carry a few (or one of those snazzy camel packs.) A flashlight or even better, a headlamp is almost a must as it gets very dark in the jungle at night. It's also important to bring warmer clothes to wear at camp since the weather up in the mountains is quite cold at night and sometimes even during the day.
Before walking the Kokoda it is also important to carefully assess how fit you are. There are incidents of people dying of heart attacks (most recently the summer of 2006) from over-exertion. There are several speeds at which one can walk the Kokoda, taking from a leisurely 10 days to a gruesome 22 hours, 14 minutes, and 1 second, which is the world record held by John Hunt Hiviki. Basically the most important thing is that you have fun doing it. Going too fast isn't fun, but taking it too slow can be boring also if you have to wait for the others all the time.