Multiple Fedoras

[Andras Simon]

I'd like to make room on a new HD for at least two Fedora installs
(and perhaps one or two other OS's, though I'd prefer to use them
virtualized), so that when F8 appears, I can safely install it without
wiping out F7 (and so on, always doing a clean install of F(n+1) on
the space used by F(n-1), leaving Fn intact). I'd like to share /home
and perhaps /tmp between them, and for the rest, to be able to mount,
say Fedora #2's /usr in Fedora #1 as /os2/usr.

Is there a sane way of achieving this? Especially wrt grub?

Andras