Back to the previous discussion of seeding in the 2010 World Cup, it seems that the last two World Cups and the last three years of FIFA rankings are the criteria.
The USA lost in the quarterfinals in 2002 (let's say 8th), they were last in their group stage in 2006 but had more points or a better goal differential than 5 teams (let's say 27th), then #20 in the January rankings of 2007, #22 in the Jan rankings of 2008, and currently #12.
I would say they can make a good case for being a top 16 squad if they finish the year strong and are the top team in CONCACAF qualifying.
While these mean nothing, I thought them interesting to see.
In 2002 the eight teams in Pot A were:
(fifa ranking from the month of the actual draw in parens)
(2) Argentina, (3) Brazil, (1) France, (12) Germany, (6) Italy, (34) Japan, (42) South Korea, (7) Spain
Teams ahead of (12) Germany not seeded - (4) Portugal, (9) Mexico, (10) England - Japan and South Korea hosts.
In 2006 the eight teams in Pot A were:
(4) Argentina, (1) Brazil, (9) England, (5) France, (16) Germany, (12) Italy, (5) Mexico, (5) Spain
Teams ahead of (12) Italy not seeded - (2) Czech Republic, (3) Netherlands, (8) USA, (10) Portugal - Germany host