In the WMTALK e-mail listserv, Kevin Unangst, a Microsoft employee, stated the following: "We are definitely planning to support WMA 9 Voice in the upcoming release of Windows Media Player 9 Series for Mac OS X. We showed the new player running with Apple's Safari browser at their WWWDC a few weeks back. We're shooting for fall release to web right now and we'll keep the list posted. Thanks for your patience"
In addition to the Windows Media 9 Series Voice codec, it appears that Windows Media Player 9 Series for Mac OS X will support all of the 9 Series codecs. Microsoft is also working on a version of the Windows Media 9 Series Voice codec for Windows Media Player 6.4.
News source: ActiveWin