Capn is correct that DTS and DD are both standard (about time for DTS).
I read an article last night that I referenced in the 720p vs. 1080p thread in this forum where the author of the article stated that 1080p would be on HiDef discs. He didn't state which format (HD-DVD or Blu-Ray), but maybe he meant that it would be available, which is different than a "standard".
As for 1080p display doing a great job with 1080i, you sure would think so, but in their tests of the latest Mitsubishi 1080p TV, they said that it had some flaws when displaying 1080i, which surprised them a little, so don't take it as everything that can do 1080p will do 1080i perfectly.
I think that it is mainly a technology issue that will quickly be resolved. It doesn't seem to make any logic sense to me why it would struggle with 1080i, but I didn't have the TV in front of me.
