Here is a small post from Phreak about the status of achievements. As many of you may have noticed, an achievments tab has set idle on your summoner profile page since I can remember
I, for one, would love to see achievements implemented in the game, but I will sit by and humbly wish that they are retroactive. I also understand that achievements present a rather tricky situation to balance. An achievement such as "Get X First Bloods" could be negative for the game. I can foresee a situation where a giddy summoner really wants to get said achievement so he pushes his lane hard and plays very aggressive. With the taste of the coming achievement enticing him, he gets a little rambunctious and tower dives the enemy only to give them first blood. Another uncertainty about them is would the summoner be rewarded for completing them. Games like World of Warcraft and even Xbox Live have had great success rewarding players for completing difficult or time consuming achievements.
What do you think about achievements and how the would impact game play? Alternatively, what are some achievements you'd love to see?
"Achievements are not coming out in the near future. They're really cool to have, and we want to have them, but there are dozens of things we'd rather spend engineering and design work on first.Phreak, Community Coordinator, via the official forums.
I mean, where would you rather we spend effort? Fixing mastery bugs, balancing Irelia, and implementing the Tribunal? Or designing the achievements, coding them in, and making them viewable on the web?"