Of course, according to Wynton Marsalis, nothing after bop is really jazz, but it's best not to listen to what he has to say

Umm, yeah.

The swing dancing community argues about this sort of thing all the time. I'm not going to attempt to speak on behalf of all the other DJs out there (some linked above), but there's plenty of "new" material done in older styles and "current" artists playing classic material. It's hard to beat the 1950's output from people like Louis Armstrong and Count Basie. Does that count as "after bop"? Whatever. In terms of current bands, there are hundreds of small combo jazz bands out there that try to play "old skool" swinging jazz. Some example include The Blue Saracens, The Yallopin' Hounds, The Swing Session, and Peter Davis's Lindy Hop Heaven. And, there are several active big bands, including George Gee's Make Believe Ballroom Orchestra, Mora's Modern Rhythmists, Bill Elliot's Swing Orchestra, or heck, even Wynton's Lincoln Center Jazz Orchestra. That last one (LCJO playing Ellington) is a particularly hot recording -- fantastic for auditioning expensive stereo speakers.