How do I setup Wordpress multi site with CiviCRM mutlisite?
I have a Wordpress multi-site that's working quite well.  Note that there are two approaches to Wordpress multi-site: subdomain and subfolder (e.g. "site1.example.org, site2.example.org" vs. "example.org/site1", "example.org/site2".

I posted instructions on the wiki page Lobo mentioned for how to set up civicrm.settings.php for subdomain multi-site.  I haven't updated it with subfolder multi-site instructions, but you can find them on my "CiviCRM multi-site checklist" page here: https://hq.palantetech.coop/projects/commons/wiki/CiviCRM_multi-site_checklist.  If you follow the instructions on that page, each site should be more-or-less independent from one another - especially if you install Eileen's excellent multisite permissioning extension (install from github, not extensions directory!)