Real & Novell have anounced that they have developed an open-source implementation of the WMV & WMA codecs. Everybody and their sister thinks this is great news, but I don't really see the point. Sure, another open-source codec is nice, but what is so special about WMV?
If I want something that sounds better than plain old .mp3 I can use .ogg and .flac. If I just want compatibility I choose .mp3.
Why would one want to use .wmv ? The same holds for video. IMHO there is no compelling reason to use either format, except if, for some reason, you want DRM.
DRM does not go down well with the Linux crew. It will be hard for any company to not create a PR disaster among the Linux crowd by openly supporting DRM. Just writing code to play the stuff is acceptable, but pushing the usage of DRM will cause a serious backlash.

It should be noted that it is allready possible to play Windows Media files on Linux, as their is software that can use the Windows codecs for playback. Having an open-source alternative is nice, but I don't think it will any significant influence.