Cheat bots in MMORPG worlds - and first person shooters, for that matter - have been a problem for many years.
I had a brief natter with Cam Robinson over at GameSpot's Reality Check for a two-part primer intro to the World of Botting for fun and profit (mostly profit).
Part 1: How Do Cheat Bots Work?
Part 2: The Fight Against Cheat Bots.
You'd need a good hour or two to go through everything involved in online Botting which is time we didn't have available, but here's an incredibly lengthy Wikipedia page which should cover most of the bases.