Description of problem:
The problem is that it is impossible to enable "extra typographic characters" from gnome keyboard properties dialog. But it is possible to enable it if pass option "typo" directly to setxkbmap -symbols.
Investigation led to following:

Xkb properties have "misc:typo":

$ xprop -root | grep XKB
_XKB_RULES_NAMES_BACKUP(STRING) = "evdev", "evdev", "us", "", ""
_XKB_RULES_NAMES(STRING) = "evdev", "evdev", "us,ru", "altgr-intl,typewriter", "grp:shifts_toggle,terminate:ctrl_alt_bksp,lv3:ralt_switch,compose:rwin,grp_led:scroll,misc:typo"

But then it does not present in constructed layout:

$ setxkbmap -print
xkb_keymap {
	xkb_keycodes  { include "evdev+aliases(qwerty)"	};
	xkb_types     { include "complete"	};
	xkb_compat    { include "complete+ledscroll(group_lock)"	};
	xkb_symbols   { include "pc+us(altgr-intl)+ru(typewriter):2+inet(evdev)+group(shifts_toggle)+level3(ralt_switch)+compose(rwin)+terminate(ctrl_alt_bksp)"	};
	xkb_geometry  { include "pc(pc104)"	};
};

And passing option directly to setxkbmap also does nothing:

$ setxkbmap -layout us -option misc:typo -print
xkb_keymap {
        xkb_keycodes  { include "evdev+aliases(qwerty)" };
        xkb_types     { include "complete"      };
        xkb_compat    { include "complete+ledscroll(group_lock)"        };
        xkb_symbols   { include
"pc+us+inet(evdev)+group(shifts_toggle)+level3(ralt_switch)+compose(rwin)+nbsp(level3)+srvr_ctrl(terminate_ctrl_alt_bksp)"
     };
        xkb_geometry  { include "pc(pc104)"     };
};


Version-Release number of selected component (if applicable):
xkeyboard-config-1.6-3.fc12.noarch
xorg-x11-font-utils-7.2-9.fc12.x86_64
xorg-x11-proto-devel-7.4-31.fc12.noarch
xorg-x11-server-common-1.6.99.901-3.fc12.x86_64
xorg-x11-server-utils-7.4-11.fc12.x86_64
xorg-x11-server-Xorg-1.6.99.901-3.fc12.x86_64
xorg-x11-utils-7.4-6.fc12.x86_64
xorg-x11-xauth-1.0.2-7.fc12.x86_64
xorg-x11-xinit-1.0.9-12.fc12.x86_64
xorg-x11-xkb-utils-7.4-5.fc12.x86_64

How reproducible:
Always.

Steps to Reproduce:
1. Enable misc:typo xkb option.
  
Actual results:
No effect.

Expected results:
"typo(base):1+typo(base):2" is added to xkb_symbols

Additional info:
The same behaviour is also on F-11.