"Safety measures" is what you wanted to use.
http://translate.google.com/ doesn't hurt.
For example somebody want to sell his coins for 10.1234 USD per Coin and accidently misses one key and is selling the coins for 0.1234 USD instead.
Answer that: how is MtGox supposed to know that you ACCIDENTALLY missed a key as opposed to using a very low rate rate ON PURPOSE?
People do crazy trades eg. when trying to manipulate the btc/usd rate. Is the purpose of a bitcoin exchange to interfere with their users' trading?
Does your bank tell you what they think about a bank transfer you are sending? No, because it's none of their business. The same goes for exchanges.
Don't trade when you're in a hurry, sick, tired, or intoxicated
Wake up please.
It just need to pop up a warning if the price you entered is like 120% or 150% different from current prices.
There is such a thing in the game EVE Online, if something cost 1000 and you type a sell order for 100 it warn you.
For example,
http://wiki.eveonline.com/wikiEN/images/a/ab/Market3.jpg it tell you the % difference from regional average.
So please take back things like
Don't trade when you're in a hurry, sick, tired, or intoxicated
how is MtGox supposed to know that you ACCIDENTALLY missed a key as opposed to using a very low rate rate ON PURPOSE?
And other hurr durr