Yesterday night I wanted to configure the Intel 2200 BG wireless card of my Samsung P35. Using YaST, this seemed to be a very easy task to do. The only problem was: it didn't work and it took me several configuration trials and restarts to find out why. Actually, being able to read helps a lot.
The thing is, openSUSE 10.3 associates the card with an eth kind of network and configures it to start when a cable connection is detected. Riiiiight... starting a wireless card when a cable is connected... Anyway, change that to "start at system startup" in YaST and restart your system (not only the X-Server) and it should work.
Another remark: KNetworkmanager can still not deal with WEP encryption keys when you need to set the key index different from 0. If you have such a network configuration, use the "conventional method with ifup" instead and configure the key in the expert options of YaST for your Wireless card.