Maybe one could connect both slots to the same controller. This way only one could be used at a time, but people could chose whether to use the card as a storage expansion (internal) or an easy(er) exchange medium (external).

In my laptop I have an additional USB port soldered internally to one of my regular external ports [1] and if the MMC controller behaves like my USB controller the worst thing that could happen when you put a card in the 2nd slot would be like pulling the 1st card without a proper umount.


[1] http://www.amilo-forum.de/topic,2449...ck-intern.html