I don't know of any built-in way to do it, I'd like to think that there is, but I doubt it.

Take a look at the following directory:
/var/lib/gconf/apps/osso/hildon-desktop/applets

It would be relatively easy to hack together a bit of a script to iterate through each directory and change all the view values from X to Y - but also there might be a magic gconf incantation to do this as well.

I'll have a think about this and see if I can figure something out for you - this is a feature I want as well, so itch, needs scratching.

Check back this time tomorrow : )

If you run this as root you can see all the current view locations for each item:
gconftool -R /apps/osso/hildon-desktop/applets