I was also coming up with something similair app (but I don't have the time now to make it idiot proof )
But I can confirm that every device mounted with the /Volumes/ command will work with VA for Mac
as long as your mounted volumes have read/write access you can read/write from within VA
I have tried CD/DVD's - network drives / USB firewire drives /NAS drives samba or AFP shares / iPod etc.
you can mount a cardreader connected to an Apple Airport extreme router or different mac's on your network
We have a mobile me familypack , you can if you want connect to another mac everywhere in the world with the 'back to my mac' function
One nice feature is that you can make an sparcebundle dmg file with 128bit AES password protection.
All my private RISCOS documents are copied to that sparceimage. - no one on the mac can open that .dmg file without the correct password
If you have an mobile me account you can even mount your iDisk and read/write to your public folder on that disk ( extra 20GB storage on the Apple servers )
as you can see endless possibilities. (yes a lot more as the humble windows user
)
<edit>
Do NOT use a space in the name of your device , it simply won't work
normally under UNIX you type a space in a filename as a '\' (eg. a drive called 'Time Machine' is under UNIX 'Time\ Machine' ), but even that won't do the trick if you want to mount such a name under VA.
</edit>