It seems that MLS cup will be at LA for the third time past 6 years. Regardless of who the contenders will be, LA will host the MLS cup of 2008, which could give competitive edge to David Beckham's LA Galaxy if they make it that far.
I can only think there is two reasons MLS has decided this move.
1. The Home Deport Center in Carson city is a nice soccer specific stadium that is capable of hosting this cup without worrying about NFL games being scheduled on the same day and stadium.
2. Media Attention: MLS is often pretty successful in filling up the stadium for that day but not so very successful to get better media attention. Well with LA Galaxy, the new home of David Beckham, hosting the MLS cup, that problem could be solved.