Since the release of StarCraft II, Blizzards has been sharing Top 200 lists for so those who wish to keep track player performances in their region can do so. Now that patch 1.2 is out, the developers are launching the Master League, which is "designed to give the best players in each region a new arena in which to prove their skill".
Over on the game's official community page, Blizzard said that Bronze, Silver, Gold, Platinum, and Diamond leagues make up about 20 percent of active players per region. Out of this group, only the top 2 percent from the Diamond League will be "promoted into the Master League".
Once players reach the Master League, Blizzard will include them into the newly announced Grandmaster League, which encompasses the top 200 players in each region. More on Grandmaster inclusion is to be provided soon, along with when to expect to be included in this elite group.
You can get more details through the link up top.