BBC Report
It's not a goal-line cam I don't think, it's a chip in the ball that sends a signal to the referee's watch if the ball goes over the line.
I think what FIFA have said about it echoes my feelings, which makes a change. Blatter has said that it will be used in the World Cup if successful, but it will be the only technology\referee-aid used for a good while yet as anything else would "dehumanise" the game.
I think it's great, to be honest. If a team scores a vital goal and it's disallowed for no good reason (Man U v Tottenham, if I remember correctly, ahem) then it's not very fair and I think this helps.
In the future I might like to see a referee consult a fourth official who watches a replay of a penalty decision as well. If it should be a penalty, great, if not, red card for the diver. End of 90% of cheating (bar free kicks around the box admittedly, but also bar free kicks in the middle of the pitch which are no good to anyone anyway). Diving ruins the modern game, and it's just not fair.
But that would be the limit for me.