This would be for everyone that wants to use a particular uncommon font without having to create images for everything. Maybe under the Manage page, administrators could upload fonts for use across wordpress blogs. This would be similar to adding fonts to a library in Flash or installing fonts on your computer. You would be able to select fonts in the editor, as well, but that point has already been made. We need a better editor for this idea to really work.
Also, it could be a per-theme setting so the font folder, or it could be under wp-content and shared across themes.