The situation with the 2007 qualifier was that neither Canada nor Mexico applied to qualify for WC 2007. Therefore USA was not an invitee but directly qualified. The qualification system is that the hosting country and the World Champions of the previous tournament is automatically qualified. Then each contintental federation (at the moment Europe, Asia and Pan America) get one spot. If there are more spots avaiable, those spots are allocated depending on the number of members of that continent. And so far Europa had 26 out of 50 members of IFAF in total. For sure in the WC 2011 will be two teams from Pan America since USA is Champion and one continental spot is allocated to Pan America.
IFAF General Secretary