I think this is by far the best idea that I have heard on this thread. We know that the ability to remove features based on karma is there (due to the inability for new people to downvote or most people to start polls), so why not remove the ability to upvote for people under a certain threshold of karma.

I think this would also alleviate the issue of having people upvote stores on the front page as a sort of bookmarking feature. I have strong opinions that many of the upvotes on the front page come from new people who are using it as a bookmarking feature and not a bestowment of karma to a good post.