By default, IPv6 is enabled in YaST Network Devices (as it should be). When running openSUSE 11.1 final, all YaST software modules requiring checking online repositories were broken. Disabling IPv6 in Network Devices allowed zypper to find repositories. 

This behavior existed in several betas running openSUSE 11.1 in a VirtualBox VM, but also in the final release on my x86_64 desktop, all using the same 2WIRE router. 

To reproduce:

1. Install openSUSE 11.1.
2. Go to YaST > Software > Software Repositories (actually any of the Software modules except Media Check will do)
3. When trying to connect to each online repository, this message will appear:

Download (curl) error for
 'http://download.opensuse.org/distribution/11.1/repo/non-
 oss/repodata/repomd.xml':
 Error code:
 Error message: Couldn't resolve host 'download.opensuse.org'

4. Go to YaST > Network Devices > Network Settings.
5. Disable IPv6.
6. Reboot.
7. Repeat Step 2. YaST connects to all repositories, can add Community Repositories, and update/install software.