We've not seen much interplay yet between the Asians, Americans and Europeans but I did watch 2 recent best of series featuring Slush (arguably the best NA based Zerg) playing against arguably the best Protoss players in Europe and Korea. He beat White-Ra 5-3 in a best of 9 showmatch and was crushed 3-0 by Tester in the final of the Gosu Coaching cup. Both series had money on the line so it's safe to say all the players involved were trying to win and I certainly didn't get the impression from those games that it was the Korean who doesn't know how to play SC2.
Demuslim has a best of series coming up against Freedom (one of the best Korean Zergs) tomorrow (Wednesday) and then another against Slush on Saturday, so that should give us a decent look at where the 3 communities stand in relation to each other.
I also learned how to defend better against siege tank on the cliff attacking your natural. Also kind of interesting that he never got any upgrades.