Look at this, http://news.ycombinator.com/item?id=1289186, 9 points in 30 minutes on the second page, yet this http://news.ycombinator.com/item?id=1288955 with 5 points in an hour is on the front page. What is the explanation?
A partial explanation for this phenomenon I have seen is that not all votes count. I haven't heard an exact reasoning on which votes do count or why votes might not be counted.