I can think of one reasonably straightforward way, which however might be really undesirable.
But before I present it, I want to discourage you from running gnome as root--I really don't think there is a good reason to do so, using su and/or sudo will give you 90% of what you need, and with a little time you will stop needing the last 10%. I won't go into a long explanation of why it's undesirable (which is my favorite euphemism for `utterly braindamaged') to run gnome as root, but suffice it to say that it's really desirable to do as little as possible as root, for your own good.
Anyways, onto my suggested solution: find the relevant config files (typically in either .gconfd, .gconfd2, .gnome, or .gnome2), and make one user's files (and/or folders) links (using ln, making them either symbolic or hard) to the other user's. However, I have the feeling that it's really a ticking bomb just waiting to blow up at you with horrible, horrible consequences. One issue is that a non-root user can do stuff to the root user's data, but I can't predict which horrible consequences will follow.