After giving it some thought I think its best that we encourage the
users to write courses in a structured language which is formatting
free. An example would be the editors used by media wiki. Or in my
opinion a _javascript_ editor which can generate docbook tags would be
even better.
SCORM does not address this issue, but there are other standards that deal with this.
My preference goes to Mediawiki, among the choice that you gave, because that solves the problem of mathematics also, since users can use LaTeX tags while authoring. Developing or using another editor that helps insert the mw encoding will solve most problems. but see below.
The other option is to use much simpler orgmode encoding. The file remains a text file without many special characters, and the file is eminently readable for human beings and does not need any special formatting. Orgmode also supports adding tags etc., which can be used as metadata.
Since, support for mw is necessary since most free knowledge exists in that format, orgmode is my choice.
Nagarjuna