I have to create a simple network of websites (different sub-domains) using WordPress. There are just going to be 3 or 4 such websites.
I know that WordPress MU was integrated directly within WordPress 3.0 and I can create a Network and use it.
Are there any pitfalls or disadvantages that I should be aware of if I go for this route?
Or, generally what are your thoughts on WP 3 Networks?
What you describe it pretty much exactly the use-case for WordPress Multisite (formerly WPMU.)
The downsides are of course that all sites are dependent on the same code and the same database so if you break one you break them all (though most of the tables are different for each site.)
Of course the upside is that you are using the same code and the same database, so you only have to maintain one set of code and one database!
P.S. There are also performance concerns for hosting too many sites on the same install (think WordPress.com), but we are talking hundreds or thousands of sites before you have to be concerned so for your use-case it’s not an issue.
There are two ways to set this up, and I’ve used both:
WP-Hive isolates the different sites a bit more than WordPress Multisite, but both are valid ways to create a network of sites.
As far as advantages/disadvantages, there aren’t that many. If you’re setting up a dynamic network (i.e. users can register and create their own subdomains) you’re restricted a bit by hosts (some hosts don’t allow for wildcard DNS settings on domains), but otherwise just about everyone supports it.
Another thing to consider is whether or not your host will let you use multisite without restriction. I don’t know if there are others like this, but Dreamhost won’t allow the use of WPMU/multisite without using their private server offering.