One issue with porting karma, rather than just being able to display different site's karma rankings on your blog or something, would be the ability to gain ton

One issue with porting karma, rather than just being able to display different site's karma rankings on your blog or something, would be the ability to gain tons of karma at the Beenie Babies site where I am a subject matter expert and then appearing knowledgeable in a commercial banking forum. On OpenID, I think the main reason it hasn't taken off is because it's confusing, actually makes a sign-in process take longer and isn't supported widely enough to be anything but a deviation in the normal UI experience to date. I think you're spot on with your points. Have another $0.02.