I'm a bit surprised to see Michael Chabon on the list; his work impresses me more like that of E. L. Doctorow than Cory Doctorow (and they're not officially related). Richard Morgan's "Thirteen" and Charles Stross' "Halting State", both great reads, made the "Best Sci-Fi" subsection. Doctorow (Cory flavored) shows up for his "Overclocked" collection and "After the Siege," a novella recently turned into an insanely great comic book, capping the six-part series by publisher IDW. Ellen Klages' "Portable Childhoods" also makes the "Collections" list, and it's freakishly good in the spirit (pun intended) of Neil Gaiman.
One thing I found with last year's list, which was heavy on Vernor Vinge and earlier performances by Doctorow: more of the sci-fi stories involve what might happen, rather than alien races, bending the rules of general relativity, space operas and human extinction. This year's list builds from an historical fiction point of view (especially Jo Walton and Michael Chabon's works), so perhaps the locus of popular science fiction opinion is shifting to helping us understand and plan for eventualities that are easily conceived and potentially instantiated, rather than those which are merely fun fictions.