I also have a Intel Centrino Ultimate-N 6300 card. Internet is working with the 11.10 live cd. I didn't want to install and update 11.10 so I took a 12.04 live cd version to test this issue and indeed an internet connection is impossible. I can conect to my WPA/WPA2 router. It shows that I'm connected, but there is no chance to go to a webpage. It's the same with Kubuntu 12.04. I did this, because I experienced the same problem with another distribution. I really get nothing, even if I stay 1 meter away from the router.
I also have a Intel Centrino Ultimate-N 6300 card. Internet is working with the 11.10 live cd. I didn't want to install and update 11.10 so I took a 12.04 live cd version to test this issue and indeed an internet connection is impossible. I can conect to my WPA/WPA2 router. It shows that I'm connected, but there is no chance to go to a webpage. It's the same with Kubuntu 12.04. I did this, because I experienced the same problem with another distribution. I really get nothing, even if I stay 1 meter away from the router.