The good news: La Casita on Washtenaw has been humming along and has recently been featuring tamales regularly. You can order them in advance by the dozen, and they're good. Until now there haven't been many places to get good Mexican-style tamales near Ann Arbor, although I guess La Fiesta Mexicana in Ypsi sometimes had them.
The bad news: Taquería Fiesta on Packard appears to be closed. There's a sign on the door saying they're on vacation with no dates on it, and no one's been there for over a month. I preferred La Casita, but I'm surprised—Taquería Fiesta seemed to be doing good business.