The Magazine of the Week is the March 2008 issue of Asimov's Science Fiction, containing "Shoggoths in Bloom" by Elizabeth Bear, this year's winner of the Hugo Award for Best Novelette. For the details of this story, see my recommendation of "Shoggoths in Bloom" when I came across it last year.
This is Elizabeth Bear's second Hugo; she won Best Short Story in 2008 for "Tideline." This year she swapped places with Ted Chiang, who won Best Novelette in 2008 and Best Short Story this year. I'm not going to do a separate Book of the Week for Chiang's Hugo-winning short story "Exhalation" (believe it or not I don't have a copy of the anthology it appeared in), but for more about him see my Ted Chiang 2008 Hugo post. Next week, the winner of the John W. Campbell Award for Best New Writer.