This post is for everyone who tried without success to setup a WPA network on their OpenWrt-enabled WRT-54G Linkysys router. So, I think that everything looking fine in the web administration tool, you choose the WPA encryption and ticked the two encryption boxes.
WPA Mode : (x) WPA1 (x) WPA2
WPA Algorithms : (x) RC4 (TKIP) (x) AES
And now, you're seeing the WPA network from your client computers ? Great. But unfortunately, you can't manage to create a proper connection to the access point ?
Well, maybe that, as I did (not) myself, you just forgot to read the nice documentation page from your friends at openwrt.org. And... probably missed the installation of the nas package on the router (the one-liner solution is stored on the linked page).