[bbcentral]

So does this prevent the links from being parsed (ie surrounded by A HREF tags?), or does it block you from posting any text that starts with "http://www"?

If I wanted people to stop posting links, I would:
Go into Admin CP->vBulletin Options->BB Code Settings
and then I would disable the Links BBCode:
Attachment 95606

So then if I was to make a post like this (with 3 forms of links):

http://www.google.com

[url=http://www.google.com]google[/url]

[url]http://www.google.com[/url]

I would get this:
Attachment 95607

If I wanted to stop the URL from coming up at all, I could always just add "http://www" to my censored word list, so if someone tried posting a link to a website it would show up as:
**********.google.com instead of http://www.google.com
Or ***.google.com instead of www.google.com

It seems much easier than installing another mod when vBulletin has the functionality built in.