Every user has their own font folder in which to place fonts.
MacOS X gladly uses standard MacOS Classic TrueType fonts without any conversion. J ason Sears asked a very interesting question regarding MacOS X and long file names. There is no information yet on Apple's site, but this is what I discovered with a little experimentation. X supports long file names. Very long - up to 255 characters, but only the first 150 are visible on the desktop when an icon text box is selected.