I can confirm this problem still exists, even in Edgy. NetworkManager refuses to connect to wireless networks, but can show them without problem. I'm actually glad to hear the acx driver has issues, since now I'm finally able to blame something for poor wlan support.
-- [dapper] NM has problems obtaining DHCP with acx_pci driver https://launchpad.net/bugs/38586 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs