Bryan Smith has an SI.com series ranking the top 75 prospects. Baseball Analysts has a thread dedicated to the list, hosted by Smith himself. The post lacks a link to the top 15, so I am adding that below.
The Pirates have 2 players (McCutchen, Walker) in the top 75 with 1 honorable mention (Lincoln).
Brad Lincoln is listed here.
The highlight quote is Linclon "should rise to the majors quickly."
Neil Walker - 60
The highlight quote is "Walker has a solid, aggressive offensive approach." He goes on to say the wrist injury affected him throughout 2006 and we should expect the numbers at the end of the 2006 season to carry over to 2007.
Andrew McCutchen - 14
The highlight quote is "quickness unrivaled for players with his power, McCutchen also profiles to steal 30 bases and win Gold Gloves down the road." Smith seems very high on McCutchen and would not be surprised to see him in Pittsburgh in a year and a half or sooner.
Considering all the top 10 draft picks we have had in the last 14 seasons, even though I know better, I would expect to see more players in the top 75. We do have some top prospects already in the majors in Duke, Maholm, Gorzelanny, and Snell. JVB, Burnett and Bullington did not qualify due to their major league experience and/or injury status for 2006. JVB, Burnett and Bullington did not appear in the 2006 listing either, only McCutchens and Walker. Duke and Gorzelanny appeared in 2005.