The ULEB Ranking has its own Wikipedia page where it is being updated more frequently than in this place.
The performance of teams in European competitions during a three year period will be used. Each club will get 2 points for a win and 1 point for a loss from the Regular Season onwards. 2 bonus points are allocated for reaching the last 16, 2 bonus points are allocated for reaching the last 8, 1 bonus point is allocated for reaching the last 4, 1 bonus point is allocated for reaching the Final. The Club Ranking consists of the sum of the club coefficients from the last three years. If two or more teams have the same Club Ranking, the tie will be resolved by the total number of wins during the three year period. Should a tie persist, the final standings in the Euroleague and if necessary Eurocup from the previous season will be used to break the tie.
The first four teams from the Club Ranking participating in the Regular Season will be 1 Seeds, the next four 2 Seeds, the next four 3 Seeds, the next four 4 Seeds, the next four 5 Seeds, and the remaining two teams will be 6 Seeds. The teams coming from the Qualifying Rounds will also be 6 Seeds.
PURPOSE As to my understanding, the three-year-ranking has two roles:
1) Providing seeds 1-6 for the Euroleague regular season draw (see column “12/13 SEED” below); This rule is already in effect for the current season and has been applied to the recent Euroleague draw
2) According to the Euroleague ByLaws: (not publicly available)
2012/2013 SEASON ONWARDS
1. A Club Ranking will be created and updated annually to determine which A-Licence Club will lose their licence and which club will replace them every year, beginning July 1, 2012.
Point 2. then describes the point system exactly as quoted above and as used in the seeding process.
*e.g. arena standards that require 10.000+ seats for A-licence clubs (only!). The new arena standards are planned to be set in place for the 2012/2013 season (source: Euroleague ByLaws)