Yes -- they were combined, and my original Midwest account was the one retained. The welcome letter mentioned that I was a MM Executive member, and that the corresponding Summit status will be maintained through 2010, and through 2011 if I have already requalified for the upcoming year.

My membership card already has an expiration of January 2012, so either they already recognized that I requalified as Summit for next year, or they are just grandfathering people in. The text of the letter is if but the card itself already shows Summit renewed for next year.