Thanks Andy, and you others, for the comments.
One thing I would say is that you probably want to
make sure that
your block devices are just xvda, xvdb, etc. instead of xvda1,
xvda2, etc. Otherwise you will run into difficulties doing
"update-grub" after installing squeeze's kernel.
I've just discovered an old post of yours
(
http://lists.bitfolk.com/lurker/message/20080529.142153.954fedf4.el.html)
which is presumably what this issue is about. I've checked my
/boot/grub/device.map and it confirms xvda (and kopt in
/boot/grub/menu.lst uses a UUID).
When I get round to giving this a go I'll feed back to the list with how
the proposed steps went. Hopefully I'll be more confident in them then and
could perhaps put them on the Wiki if deemed useful (at least as a
starting point for further fleshing out).
Mathew