Are you using Mac or Windows?
On my Mac, all these presets are stored in users/tokengirl/library/adobe/lightroom. I'm not sure where they would be on a Windows machine, but I'm sure you'll find them if you hunt around.
I have copied some of my Develop presets and shared them with friends via e-mail or cd-rom, so I guess you could do the same with other presets??? Never tried to share anything but develop presets before.