This is Linux. Anything is possible.
There is a project called Grub4DOS which will put a Linux bootloader on an SD card so when you boot you are presented with a menu of which Linux image you boot.
http://sourceforge.net/projects/grub4dos/
However if you are new to Linux you will probably struggle to get it installed and set up.
By far the simplest solution is to just swap SD cards when you wish to change OS.
You will of course have to choose a distro built for an ARM architecture to use on your Raspberry Pi which rules out Mint (and maybe Ubuntu too I am not sure).
The easiest distro to get going is Raspbian, but I recommend checking out Arch Linux too since that is what is under the hood of Rune audio. There is nothing preventing you from installing other Arch Linux packages on Rune and using it as a general purpose computer. The Arch package management system is called 'pacman'. The Arch Linux wiki is very informative if you want more info.
