I wonder if a side effect of WebM will be to push Ogg Vorbis into wider adoption? Platforms that want to play WebM will also decode Ogg, so why not support the audio-only format?
Much like Theora, the primary reason to oppose Vorbis is political. It's not covered by patents and doesn't support DRM, so to content providers it's a significantly worse codec than MP3 or AAC.
If Apple or Microsoft were going to support Vorbis, they'd have done so years ago.
It's main problem is network effects, in cases where network effects don't apply, e.g. game audio and web streaming audio, it has longe been used by big names such as Microsoft and Spotify.
There is now no reason for it not to be the standard for web audio, since you can even fall back to Vorbis in Flash 8 via a non-native decoder. It's also likely to get a boost in the pirate video market, even when paired with H.264 as a result of WebM introduction. It really could become mainstream for a variety of uses.
The biggest drawback in the last few years has been the lack of support in iPods. It will be interesting to see if Apple chooses to prevent you playing Vorbis audio on your iPod Touch even if it caves and allows it for web audio.
Didn't you mean AAC?
http://www.tunequest.org/a-big-list-of-mp3-patents/20070226/
(I'm not an expert at all.)