The World of Warcraft: Wrath of the Lich King Website announces that achievements will be added to World of Warcraft with the release of the Wrath of the Lich King expansion. Here's a bit:

World of Warcraft’s achievements come in several varieties. Some simply require specific actions to unlock, such as getting a haircut or defeating a member of each race in your opposing faction in PvP. Others involve a progress bar and require you to do something several times -- such as give out 10 hugs. Some achievements are progressive; for example, once you complete an achievement to collect 10 vanity pets, you might next be asked to collect 25. Finally, meta achievements unlock when you complete other achievements -- unlocking all World Exploration achievements (see below) unlocks a World Explorer meta achievement. Some achievements, including those that involve quests, honorable kills, items currently in your possession, skills (including professions), exploration, and reputations, will be applied to your character retroactively.