I have spent the day starting the core solution to multidomain/subdomain sites. I used version 2.3.3 RC to make this build so it is with unknown issues, I know some of you are working with this version from the nightly build.
The way this version works is you follow the install as usual, in the system module there is a new option called "Domains". This allows you to add domains to the system and assign themes and languages for the site.
This is very useful for example imagining that you would set your domains up like so:
http://en.yoursite.com (english + theme)
http://fr.yoursite.com (french + theme)
http://cn.yoursite.com (chinese + theme)
http://uk.yoursite.com (english + theme)
What you do is point your subdomain at your XOOPS_ROOT_PATH and the system will make adjustments to setting based on your domain abstractions.
if you want to download this and give it a test please do so from http://bin.chronolabs.org.au/MultiXoops-2.3.3-rc.zip (6.9Mbs)