Can WordPress Have More Than One Subdomain?

Can a multisite exist with just one WordPress Installation, or do I have to have a wordpress installation for each subdomain? I want each subdomain to have its own home page. I don’t want them to have the same home page.

Also is it possible to have Global Login?

http://news.boingblogs.com/
http://blogs.boingblogs.ocm/
right now there are two installations of wordpress. can I have more than one wordpress with just one installation?

Sorry for the annoying questions. I am new to wordpress.