Thanks for all the replies.
Sportrider: Glad to hear I'm not the only one, though I do still wonder why some bikes howl and others don't. I too thought wheel bearing, so I'm glad to hear that's probably not it. Mine's blue, so the afterburner theory is out, but I do have the extended warranty so I'll probably schedule a visit to the dealer in the next week or so. I'll let you know what I find out.
boliviasi: Nice picture, is that you? Maybe I'll just print that out, put it in my map holder and that'll help me forget about the howl. BTW, I bought the bike used about a month ago with 2500 mi on it, so I may actually ride more than you ;-)
fz6xlr8r: It's definitely not engine, though it could still be drivetrain. Pulled in the clutch and nothing changes, but that only eliminates motor back to clutch, not tranny. I suspect I would get the same noise coasting downhill in neutral with the engine off though. That would be a wicked hill though!
wrightme43 & bcityroller: I think you're probably right. I may experiment with duct tape and see if I can locate the pocket/hole/gap that could be causing it.
Thanks again for all the feedback and I'll post my findings if and when...