Just spent 3 days getting this going, so putting this here for future reference.
To get WPMU working on (mt) (dv) server using subdomains (ie. blog1.domain.tld, blog2.domain.tld, etc), first follow the usual step of setting up a wildcard domain.
If you do it right, you'll have something (usually the default MediaTemple screen) come up at blog1.domain.tld, etc. If it's not right, you won't be able to connect to the address.
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The httpd.conf you have to edit is NOT the one in /etc/httpd/conf (like some tutorials say); you want the one in /var/www/vhosts/domain.tld/conf.
Type the following (without quotes) to get at it (replace domain.tld with your actual domain name):
"cd /var/www/vhosts/domain.tld/conf"
Then type:
"vi httpd.include"
You'll be in the editor now. Add the *.domain.tld under ServerAlias.
Restart Apache and you're good to go. FINALLY. Hope this helps someone.