Starting from the 3.0.0 release, Wordpress MU and the single-blog variants have now been merged. Remember the post on how to create a BuddyPress site? I did the installation on a single-user blog then. One reason why I did not try it on the MU variant required some modifications to the server's configuration. It was something on the lines of editing the .htaccess file (can anyone remind me?). I hope this technical requirement is now done with. With its famous five-minute install process, you can create your own microblog quite easily. Try it (and may be inform about it, ;-)).
Check out the Wordpress MU site. Things have changed now.