http://eu.battle.net/sc2/en/blog/4055892/World_Championship_Series_Overview-13_04_2012#blog

A great opportunity for all Starcraft 2 players. They will be adding more countries for the next edition, and an info for all not supported countries will be offered in the coming weeks.

Most likely every Starcraft 2 player will be able to compete (I think those coming from countries that aren't directly supported will have a chance to get in through the official ladder).

eSports is getting bigger, yey!

EDIT: Here's to hope that Valve will do something similar with CS:GO and DotA 2.

Valve are doing more than similar to this with Dota 2 even in beta. The Dota 2 eSport community is growing everyday.

About the Blizzard tournament:
So far I've noticed couple of issues...Not good spreading of slots by quality of players... for instance - Ukraine have 2 slots ...and guess who will take them - Dimaga & WhiteRa..Other European countries that don't exactly show up on SC2 scene are with 3 slots...
I believe that Korea will get most slots for Asia - that is normal for sure...

Time will tell I hope Blizzard give a chance for other players besides Koreans to win this.