I reported similar bug, but this was refused/unfixed.
I must say something before : currently, keyboard config on mac is prettry ugly, especially for french users : gfxboot does not allow language and keymap selection. And even if user select macintosh/fr from the keyboard config applet in Gnome, the keymap is unusable : no [, |, ~, }, € and other important symbols. This keymap also do not allow VT switching which may be very critical.
I saw a lot of french mac user giving up using Ubuntu on their mac because of this problem.
This is why i ask for a quick inclusion in dapper of an updated symbols map for french user.
The symbols map is available at http://bersace03.free.fr/pub/Linux/xkb-mac/fr and must replace /etc/X11/xkb/symbols/macintosh_vndr/fr
I also mention that using lv3:lwin_switch make VT switch impossible on mac. This must be disabled for mac, at least french one.