FYI: The newest kernels have "namespace" support. Ordinary users can create a namespace, and within that namespace, become root and do fun stuff like mount file-systems.
It doesn't give you "real" super-user permissions though -- you can only do what you're already allowed to do (i.e. you can only mount devices that you can already read).
http://lwn.net/Articles/531114/ See section 4.