With the migration from WordPress MU (MultiUser) to WordPress 3.0 (Multisite), I think there is a need for us to clarify some terminology. On the wp-hackers mailing list, I’ve seen several instances where people used the word “site” to mean different things, depending on who is writing, and the context of what they are trying to say.There is some overlap currently between how we discuss an individual site within the setup, versus the overall system which contains those sites.
In WordPress MU, the term “site” tended to refer to the overall installation, covering multiple “blogs”. With WordPress 3.0 in Multisite mode, some people are conflating the terms “blog” and “site”, and it appears that “site” would be the preferred term. The new term for the overall system is “network”, as evidenced by the new Network Settings page. So instead of a “site” which contains multiple “blogs”, we have a “network” which contains multiple “sites”.
The change in terminology might cause some confusion at first, especially among people who are already familiar with WordPress MU, and are used to the old terms. But I think that saying “site” instead of “blog” is better, because it avoids confusion for people who are building websites that are not blogs. With that in mind, it makes a lot of sense to talk about a WordPress installation as a network of sites.