NetEase, the operator of the three Westward Journey games, Flyff (and here's the American version of Flyff), and the 100 pound gorilla that is World of Warcraft, is in a very unique position to speak on the troubles botters present to online communities. Westward Journey and World of Warcraft both draw huge numbers of people in China, but that also means they draw a huge number of botters.
NetEase has fought against this rising trouble by utilizing captcha and logic questions, such as "Which of these characters is facing right?" when presented a picture of a group of characters facing left while one is facing right, before characters can initiate combat and other types of money making activities.
Botters, however, have gotten around these problems by making sure the bot program alerts one human user and then switches back into human control for just long enough to let the single man enter the captcha or solve the logic puzzle. In this way, one user can control multiple accounts simultaneously while still fooling the system.
So how does NetEase continue their fight against botters? Well, check out the whole article over at Gamasutra to find out how progressive gameplay and online communities aid in the struggle against MMO botters.