Single WordPress Core – Multiple sites

Most of the ability to create a WordPress Network is already built into the WordPress core, but you may need a plugin for domain mapping.

The only warnings that I’d give you is that extracing a single site from a network can be a lot more tricky then doing it for a single-site installation. On top of that, in a netowrk, the user base is shared amoungst all of the websites, so if someone is set up on one site, they’ll be registered on all of the other sites (as a subscriber unless an administrator changes that). That may or may not be the way that you want to work.

If the only reason for this is conserving space, then I’d suggest against it. Server storage space is pretty cheap these days, so adding emough for even a fiarly large WordPress site isn’t going to be prohibitive. We’ve got most of our sites set up on a couple of different reseller accounts, and we’re running somewhere around 40-50 sites out of them for not a huge bill.