I think the biggest problem is to guarantee that some future civilization will not dig up the waste believing it to be valuable, like we did with the old Egyptian graves. We could make it very difficult to do so, but it's not a "solved problem". http://vimeo.com/55736976 is an interesting watch (although perhaps a bit biased).
It's a solved problem. Dilute it with sand until it is about as radioactive as the original ore, melt the sand, and dump the chunks of glass someplace out of the way. Yes, future generations will need to protect themselves from it, but they already need to in huge areas where the ground emits radon.
