Leroy Jenkins has gotten back together with Sirone and Jerome Cooper, and that might be the best news in jazz this yearespecially since the new And Now . . . makes the five 1970s LPs that established the Revolutionary Ensemble as an avant-chamber group comparable to the Modern Jazz Quartet sound like so much unfinished business. Beginning with Sirone's "Berlin Erfahung," a rouser in the style of the Art Ensemble's "Odwalla," the heads are riffier this time aroundeven devotees of free improv crave an actual tune now and then (as do the improvisers themselves). It also helps that their dour humor has moved up front, nowhere more than on Sirone's "Ism Schism," which achieves a Viennese stateliness while mocking the very notion. Though the basic instrumentation remains spartanviolin, bass, drumsthere's no lack of color in the three-way exchanges. Throughout, Sirone bows heroically, Cooper implies several beats on different parts of his kit, and Jenkins again shows that a violinist can think microtonally without imitating a saxophone. Music this interactive and close inevitably risks seeming sealed off, but on the lengthy "911-544," where Jenkins doubles on harmonica and composer Cooper adds real-time electronics, balafon, and double-reed instruments, it's as if they're opening a window and letting the world in. The title's first half is obvious, the second the street address of the East Village apartment building from which Cooper watched the towers collapse. But you don't need to know the specifics for this powerful piece to get its grips on you.