It looks like major browsers (like firefox) will not support it for quite a while, for different (and as I read difficult, political) reasons. We shouldn't rely on people being able to display such files for a while it seems.
Having said that (and in order to resolve the issue one way or another): should a repo be created or not?
If we have no thorn that actually uses it (a la IOJPEG), I am not sure I see the need (but if someone wants to package it up this is also fine with me -- as long as it does not break compiles, take long to compile or add extra dependencies :-) ). If someone wants to update eg IOJPEG with extra formats then this would seem to make more sense to have the external library.
Let's close it until someone either needs this, or volunteers to do this.