We know they're important.  They just released updates for them.  There are movers and shakers.  Some slip, some rise.  But in the end, they're just educated guesses on talent and recent performance.  But the rankings, as well as McD's All Americans, are merely recognizing what some players have done, not what they'll do.  What they'll do depends on a variety of factors, including choosing the right system to play in, health, and outworking your opponents. In the end, the educated guesses are right for a good number of players, But for the 2002 Mickey D's class, things didn't turn out that way.  

http://www.cbssports.com/collegebasketball/story/15421905/class-of-2002-serves-as-a-cautionary-tale-for-todays-allamericans