It was added on 11 April 2007.
The slippery bridge in Olaf's Quest wasn't quite working how we intended, which resulted in a lot of frustration. We never like our content to be frustrating - we prefer it to be challenging (there's a big difference!) - so we've tweaked the calculations that sort out whether you succeed.
Originally, the bridge was designed so that you had a reasonable chance of passing each individual step, which seemed right to us... Unfortunately, with 12 steps in a row this all added up to a very annoying part of the quest. We're really sorry for this, and would like to thank all of you for persevering in the face of this mistake and trying to finish the quest anyway. It's a testament to your dedication to the game!
What we've done now is to make your character learn every time he or she slips, so the more times you fall the more likely you are to get past it. We haven't 'nerfed' the quest - high level Agility is still a big advantage and will still really help you cross the bridge much more quickly than players with low level Agility. It's still pretty challenging to get across, but hopefully a lot less frustrating because at least now each time you fail you know you've got a better chance next time you try.
As stated on the original quest page high agility is supposed to be an advantage for this quest (not an outright necessity). That was always what we intended, and so that is now how it works. Hopefully, this will make the quest much less irritating so you can focus on the story and get to the rewards!