CONCACAF stands for the "Confederation of North, Central American and Caribbean Association Football", and the CONCACAF Champions League is an elimination-format tournament that includes the best pro teams in each member country. It is essentially the regional equivalent of the (much more famous) UEFA Champions League in Europe, which is generally won by top-flight teams like AC and Inter Milan, Man U, Barcelona, etc. LA Galaxy is in the CONCACAF tournie this year by virtue of having had the best record in MLS last year, even though they ultimately lost MLS Cup to Real Salt Lake (who are also playing in Champions League). MLS is one of the only soccer leagues to use a playoff format...most just award championships to the team with the best record (kind of like baseball pennants back in the old days).
DC United has been in the CONCACAF Champions League like 10 times (4 MLS Cups, several "Supporters Shields" for the best regular season record in MLS, plus a few US Open Cups [another tournie open to US pro teams of all levels, analagous to the FA Cup in England]). Meanwhile, MLS league play proceeds apace. The stronger teams that get invited to one or more of these tourneys on top of regular league play can get worn down really fast. At any rate, the winner of the CONCACAF Champions League will ultimately play in the club World Cup against the winners of the other regional confederation tournaments, so it is pretty prestigious.
Clear as mud?
