The mobile version of mobile.live.com does not work *at all* with Opera for Windows Mobile (which is installed on all new HTC devices - including HD, Diamond, Touch Pro, Sony Xperia and Samsung Omnia). Instead you see the desktop version of mobile.live.com.
Renders all of the useful Windows Live mobile features completely useless. Users can view it with the mobile version of IE, but IE is buried away out of site on the above devices that the average user would never find it anyway.
Should just be a matter of tweaking the browser definitions.