"A-matter" is newspaperese for the key facts about an event--the "top" of the story. "B-matter," then, is everything else--the extraneous color and details that may be cut from the bottom to fit a story to a page without detracting from the import and impact of the news.
In the so-called war on terror (or whatever it's known as), anything to do with Islam as the inspiration of terror is always an extraneous detail. Here's paragraph 12 from a Washington Post story today about Mumbai headlined: "Details Emerge from Sole Arrested Gunman." The paragraph begins with a quotation from an interrogator describing the surviving jihadist's--sorry, "gunmen's"--extensive training.
"He went through different stages of training. At first, it was the recitation of the Koran and lectures about jihad. He was being prepared mentally. Then small-weapons training," Bharti said in an interview. "Then came the hard physical, marine training. At first, Kasab used to vomit. They were taught how to survive at sea, on ground, and how to control thirst and hunger. From a batch of about 25, 10 were handpicked for the Mumbai mission."
Details, details. Recitation of the Koran and lectures about jihad = B-matter. No wonder we're losing.