If you were to run 20+ wordpress blogs, is there a way to centralize the management? Or would you have to log into each one individually to change/update something?
There is no more "Wordpress MU". Wordpress 3.0 has network capability. You can manage a blog network or multiple blogs from a single Admin panel. You can set your network up as subdomains, folders, or use custom domains with domain mapping.
I second that, I did not realise MU was no more either. Tres Ineresting (ya I know I probably spelled that completely wrong but you get the idea)
Here is more on activating the Network Features of Wordpress 3.0: http://journalxtra.com/2010/06/activating-wordpress-3-0-multi-site-formerly-multi-user-mu/. It's pretty easy, just make sure that you hosting is in order.
Yep with Wordpress 3.0 wpmu merged into wordpress... you just need to activate the features... Here is the step by step guide from wordpress.org for what you want -> Migrating Multiple Blogs into WordPress 3.0 Multisite
wordpressinstaller.net this service offers auto wordpress installation, configuration, theme n plugin installation + configuration and best of all, it's FREE. u can also manage all your installed blogs at same place without need to login at all blogs individually. have a look at that, u will like it.