For some reason on Fedora 16, NetworkManager VPNC dialog won’t appear as expected. When I click the VPN Connection from the menu, nothing appears. I have to kill the /usr/libexec/nm-vpnc-auth-dialog process twice before it actually displays the prompt. This happens every time I want to use vpnc from the NetworkManager drop-down. I’ll be experimenting to see if this occurs after reboot or just from suspend.
NetworkManager-openswan works for me against Cisco VPN pretty well. Just saying.