WordPress 3.0 in a subdomain

Ok, I have upgraded to the newest nightly build of WP 3.0 Single user is fine and working without a hitch (once I found that the TSG podcasting plugin was borking the taxonomy.php) I was wondering, if it is possible to creat a multiuser WP if it is installed as a subdomain already… I know multiuser works on my host and I was using it in root https://twittrblog.com but changed to a subdomain install (now https://blog.twittrblog.com) anyone have any clarification?