You often hear about the two versions of WordPress – .com and .org. With the .com version users get a free, easy to use version that is limited in functionality and not very customizable. With the .org, users get a self-hosted version that is fully customizable but requires programming knowledge.
Developers have built an industry around the .org version creating and selling premium themes and plugins, offering membership to support sites, or creating custom sites for clients one at a time.
With the addition and growth of MultSite (formerly MU), WordPress is capable of a whole new way of doing things, bringing the best of the .com and the .org worlds together.
By creating a premium WordPress MultiSite installation targeted to a niche market, it is possible to provide an easy to use end user experience that provides premium themes and plugins and a level of customization tailored to that market.