I think they changed that rule at some point around 1983.
I guess it was 1997 - it was just the extreme animation of Almunia that really caught my attention - all on the goal line, so legal.
Law 14 - Penalty Kicks
The only time during a game a goalkeeper should be standing on the goal line is during a penalty kick, and that is only because the Law says so. Goalkeepers are allowed to move side-to-side along the goal line, but not to move forward until the ball is struck.
Why is this Law disregarded so often? Moving forward offers the goalkeeper a host of advantages, from a better catching position to narrowing the size of the net the shooter sees. Why isn't it called more often? Tradition, mostly. This is one of the most inconsistently called Laws in the book, especially for one that isn't even a matter of opinion. Until FIFA decides referees are going to enforce this one to the letter, or the rule is rewritten, we will have to live with the inconsistency
The penalty kick was introduced to soccer in 1891 to combat the growing use of illegal means to prevent goals, particularly by handling the ball. In 1905, the requirement was added that the keeper stay on the goal line until the ball was kicked. This denied the goalkeeper the liberty to advance up to six yards, which resulted in "too many" unsuccessful penalties. In 1929, a prohibition on the keeper's lateral movement was imposed, but was generally ignored. This Restriction was repealed in 1997, in recognition (or resignation?) of the fact that goalkeepers were moving along the line anyway.
As the Laws of the game of soccer currently stand, the goalkeeper must be on the goal line between the goalposts, and may not move forward until the ball is struck. All other players are outside the penalty area, at least ten yards from the ball and behind it. The shooter is identified, the keeper and other players take up their position, the referee signals, and the pressure is on!
http://www.jbgoalkeeping.com/pks.html