From the brief article with the rankings:
"It can safely be said that the panel we assembled in order to put together this listing was the biggest and most geographically spread panel which has ever been amassed to judge the merits of golf courses. They included the great and the good from all corners of the planet, all experts in their own fields, taken from a diverse cross-section in the game. The panel were asked to consider design, conditioning, history, memorability and reputation.
It is worth mentioning that Golf World produces the most respected list of the Top 100 Courses in Great Britain & Ireland (November 2008), plus the Top 100 in Continental Europe (November 2009). For the purposes of this list, the order of these rankings was not changed."
They don't say who the panel really is, but I'm glad they consider history and reputation in making their selections!
Also, the latter paragraph shows how they come up with somewhat skewed results ... they decided they had to keep the courses in the same order as their own European rankings, which have always seemed quite strange to me because they are so different than how outside observers rank the best European courses.