I have a new aluminum imac 2.4 ghz intel core duo 2 20"monitor. I dual boot with Ubuntu and OS X. With Ubuntu 7.10 installed the keyboard worked normally. When I upgraded to 8.04 the keyboard will only work with keys around the uiop keys acting as a keypad.
I can use the F5 and F6 keys to get to a console (tty5 or tty6), but then can't get back to the desktop or go to any other consoles. The keyboard works normally in the consoles.
I can log into the desktop using the keyboard, but then the keyboard stops working. The keyboard is the 105 key US alternative - international which is installed by default.
Since I upgraded from 7.10 I can use grub to boot into the older kernel. When in the old kernel the keyboard works normally. If I attach a standard PC keyboard, then 8.04 works normally. The old kernel from 7.10 is 2.6.22-14-generic. The new one from 8.04 is 2.6.24-16-generic.exhibits
The keyboard exhibits the same behavior if I boot to the Live CD for Ubuntu 8.04.