According to the news over on AVPlay both Kill Bills are coming to the UK September 3rd. There might be a chance of a Japanese HD-DVD release for KB as I know the first one was released by Universal there on DVD. US and UK are covered by Buena Vista so BD only.
Casino Royale is Sony's globally, so there's zero chance of that coming to HD-DVD anytime soon.
Gladiator is distributed by Universal, so should appear on HD-DVD at some point.
300 is Warner, so will be out on both formats (rumour is a late summer release in the US).