A list of publications covering Jazz, Classical, experimental, and so on, is comparatively quite depressing. In Jazz specificially, this situation arises not so much due to an excess of lemming sycophants, as in Rock genres, but because of sheer lack of interest. Thousands of listeners, not hundreds of thousands, devote a fair amount of time to listening to new Jazz, especially that which is not traditionalist in some fashion. Signal to Noise, mentioned previously, is switching to biannual publication. For traditionalists (you know... Woody Allen?) the Mississippi Rag is apparently gone with the passing of its editor and founder Leslie Johnson. You've got the mainstream rags: Jazz Times, Down Beat, Jazz Journal, Jazzwise, and Jazziz; two fine New York-centric publications (New York City Jazz Record and Hot House). Cadence, with its curious mix ranging from the Blues to Free Jazz, and previously connected to an eponymous major mail-order/online retail operation (now called Klompfoot), is being revived as an annual; the fate of the Canadian publication Coda, which for many years was the best among those covering modern/ avant-garde/ Free Jazz, is still uncertain, having gone on extended hiatus. While I'm only discussing English-language publications in these posts, the Jazz world is served by publications in Germany, Japan, and elsewhere to a greater extent than Rock music.
Stretching beyond Jazz, the situation seems better, though the U K magazine Avant is gone, following the London Musicians Collective's usually-excellent Resonance. The Wire helps tremendously, though it toned down its coverage of the Jazz avant-garde for much of the last decade only to pick it up again more recently. That publication's unpredictability with regard to what music gets covered presents several barriers to its relevance for post-Classical/ modern Classical/ post-Rock experimental/ avant-garde Jazz musicians. Artists whose releases have not been reviewed in some time will suddenly grace the magazine's cover. Artists with huge followings like Radiohead or Wilco get high accolades for brief moments, then get ignored again. It should be renamed the Waver.
Music Works, a Canadian voice for experimentalists, could be said to be the global voice. Two cheers for the Canadians--that is, if Coda comes back--because these publications know what they're doing and do it well. Plenty of academic journals do too (The Leonardo Music Journal, the A R S C Journal, Jazz Perspectives, Popular Music and Society, and a smattering more), but we're leaving those aside for now.