I was tired to update all the blogs on every change of Wordpress or one of the Plugins and so I decided to move everything to Wordpress mu.
But I don’t need several blog in subdirectories (ie. domain.ch/blog1/, domain.com/blog2) neither in subdomains (ie. blog1.domain.com, blog2.domain.com). I needed them on own domains (ie. domain1.com, domain2.com).
