Linux Multiboot

Hey everyone. I've been dual running Windows XP and Linux for about a year and a half now (currently on Ubuntu 10.4). I've noticed when installing that you can mount certain folders for each partition. For example, the /tmp, or /boot.

What I've been wanting to do is keep XP and run, for example, an Ubuntu and a Kubuntu in a triple boot setup. I'm curious if it's possible to set up three ext4 partitions, one mounted with /boot and the other two mounted only with /, so that both distros can share the same /boot directory. Or am I totally misunderstanding the function of the partition mounting?

Thanks for any input.

i wouldn't share the /boot between the two, only /swap and /home should be shared

Instead of installing Kubuntu on separate partition, you can install KDE in Ubuntu only. I have installed both in my test machine.
As coopstah13 mentioned already, its not a good idea to share /boot partition. You can share SWAP, /tmp and a few other partitions.