Today Apple released a high-definition version of the Harry Potter and the Goblet of Fire theatrical trailer on their website. Quicktime 7 Pro is required to view the file (or you can get the alternative.
Happy viewing to those who have that software. Thanks to Peter for the tips!
UPDATE 2: If your computer can't handle the loading (or you simply can't wait), there are now a handful of high-definition screenshots and stills online for your viewing pleasure (warning: spoilers). Thanks to Oliver of IntoThePensieve for the tip!