UPDATE: I can now confirm that this report is true, and I've used the beta version of the Audible app. It's real!
A post on reddit claims that the long-awaited Audible app for Windows Phone is now in limited beta and will be more broadly available soon.
"If you're like me, an Audible app has been one of the last major omissions in the WP Marketplace," the post notes. "Well, the wait is nearly over! The WP Audible app has entered a limited beta ... A wider beta program will be announced in the near future."
OK, that's not much to go on. But here are some shots of the purported Audible App for Windows Phone.
Thanks to Peter M. for the tip!