Do Ubuntu and Mac OS X place nice with each other?

[Seth]

So, a few weeks ago I made a thread that I was getting a MacBook Pro
and was wondering if I could just partition the drive with the Boot
Camp Assisstant and install Ubuntu. Well, I decided to do it. I have
my CD sitting here and I am about ready to partition the drive. The
main and most important thing I want to know is if I will still be
able to boot into Mac OS X. Does GRUB install itself on both
partitions or just the one that Ubuntu is installed on? I'm probably
going to install Ubuntu regardless, but I just want to know if they
will play nice with each other.