Looks like the Chumby has no problem accessing the Mintpad's file system for playing MP3s.  Seeing these two connected together makes me very happy.  I think they were made for each other.

Can't tell at this point if it can access the Mintpad's internal and external (SDHC) files at the same time, but I'm really excited that I didn't have to do any modifications to get this working.  Now to find other applications.  Creating a Mintpad/Chumby webcam rig is at the top of my list, but that's probably a bit over my head.