The default Apache configuration in Intrepid breaks any name-based virtual hosts you have defined without a port number. The fix is to add a port number to your virtual hosts (<VirtualHost *> needs to be <VirtualHost *:80>). The Launchpad bug is here, although it's not really a bug. Here's the full explanation from the NEWS.Debian file:

The directive "NameVirtualHost *" has been changed to "NameVirtualHost
*:80". It has also been moved from sites-available/default to ports.conf.
This allows to ship a proper SSL default virtual host config in
sites-available/default-ssl, but it means that if you use several name
based virtual hosts:

- you will have to change <VirtualHost *> to <VirtualHost *:80> in your
  name based virtual hosts

- you need to add more NameVirtualHost directives if you use other ports
  than 80 with name based virtual hosts. You may also have to add these
  ports to the default virtual host in /etc/apache2/sites-available/default
  (like this: "<VirtualHost *:80 *:81>").

If you prefer to revert to the old setup instead (and don't need the
default-ssl host), just change "NameVirtualHost *:80" back to
"NameVirtualHost *" in ports.conf and "<VirtualHost *:80>" to
"<VirtualHost *>" in sites-available/default.

Hopefully, Ubuntu will have real release notes when the final release comes out, but in the meantime, I hope this saves someone some confusion.

changed October 4, 2008