I am not getting problems with IE10 font rendering on Win8. It does not seem bad and with IE and Firefox side by side they seem almost identical.
Except for wrong colors in IE because it does color management very badly.
The text in Windows desktop and in the Metro start screen is mostly rendered well, must be with cleartype. However from time to time a notification shows with extremely badly rendered greyscale anti-aliased text (e.g. on the login screen, power button, menu to select sleep, restart etc.).
I have not used any metro apps yet. But Microsoft advertises the Surface as a "cleartype" screen, so presumably it is available for programs to use?