OGG/OGM media container

Hi all,

Xiph aims at developing open-standards media formats. Though xiph.org 
tells about vorbis/theora/flac/speex, nothing is mentioned about container 
to use (that is ogg/ogm). I have a few questions

Is there a difference between ogg and ogm? I guess its only the extension 
that is different and everything else is same.

Some tools (like ogmtools) are available to create ogm files. What is 
state of that code? It it stable? Is it advisable to start convering my 
AVIs to OGMs? ogm specs are final or they will probably change and are not 
yet final?

If answer to previous question is yes, why mencoder don't produce ogm? Why 
people are still sticking to AVI? Is it just lack of time/energy of 
developers or something more technical?

What are main advantages/disadvantages of matroska(http://matroska.org/) 
over ogg/ogm? Why 2 different projects? Why not ditch one and concentrate 
on one?

Why www.xiph.org don't provide any info about ogm? I was not able to find 
specs. Also, xiph.org doesn't link to any of ogmtools site.

PS: I have recently joined xiph team as webmaster of xiph.org, and if I 
get answers to above questions I can create a page of ogg/ogm at 
xiph.org with details about same.

Nilesh Bansal
http://www.cse.iitb.ac.in/nilesh/