<< No, Macs have WMP as well. Linux doesn't - YET. >>
Bill Gates throws bones at Apple to give the impression that MacOS is competition for Windows. He produced WMP, Office, IE for Mac to make it seem like the MacOS desktop is a viable competitor to the Windows desktop.
It isn't. The MacOS dektop runs on proprietary hardware that only Apple makes. Apple abandoned their OEM hardware plans a long time ago, so Apple hardware will never become as cheap or as widely available as Intel compatible hardware. There is a reason that the word "PC" is synonymous with "Intel compatible hardware" and that reason is market penetration. Apple by itself can never achieve the kind of market penetration that hundreds of vendors competing with one another and building on common standards can. Apple serves a niche, Apple knows this, Bill Gates also knows this, and that's why he's not too worried about making apps for the Mac desktop.
Linux on the other hand runs on the same widely available and cheap Intel compatible hardware that Windows runs. (Alongside a bunch of other architectures) If there's a candidate that can challenge Windows on the desktop, Linux is it. Bill Gates would commit suicide before he would produce any apps that would make Linux a more viable desktop solution than it already is.
In short, wma is not coming to Linux anytime soon. It's not coming to the cheaper, more affordable mp3-CD players. It's not coming to your set-top box. It's not coming to your digital-music enabled stereo component. Because, frankly, these embedded devices are already sold at razor thin margins, and they have to get away with using as little hardware as possible. You need Win XP to play licensed wma's. Win XP Embedded will not run on an equivalent of P133 with 16 Megs RAM. Win XP Embedded will not run on StrongARM, Dragonball, Coldfire, or any of those other low-cost low-power system-on-a-chip solutions. Linux will. Linux will run on these architectures, will cost nothing, will play ogg's, and this additional functionality will also cost nothing. Linux and Ogg Vorbis will also provide the consumer with the kind of convenience that licensed wma's can't. Case closed, gentlemen.
P.S. You may claim that licensed wma's are nowhere to be seen. You would be wrong. Follow up with Napster and MSN Music over the next few months, and they will move to distribution SOLELY in licensed wma format.
Microsoft is making a great push to get consumers to accept crippled, licensed music. Ogg Vorbis is our only hope of getting consumers to see that they can get better music quality at smaller file sizes without having to out up with Microsoft's crippling licenses.