They're using Github and Google Groups to plan EmacsConf? Neither of these systems are free software. RMS will be unhappy.
org files work well on Github. I've got an open issue that would make using org files even more usable.
https://github.com/github/markup/issues/473
If this gets fixed, it'll be easier to maintain a blog, site, etc on Github with org files.
I didn't know that Discourse had community wikis. Then we can switch off of GitHub too (plus, git is a bit heavyweight for what is essentially a wiki doc :) )