I was wondering when this would happen. Previously, you could only rent TV shows and movies in HD via the Apple TV. Now you can buy, and do it all from the PC:
Apple today announced that iTunes customers can purchase and rent box office favorites including "Quantum of Solace" and "Twilight" in stunning HD on the iTunes Store (www.itunes.com). Starting today, movie fans can purchase box office blockbusters for download in HD for $19.99 from iTunes, and films will be available as iTunes Movie Rentals in HD for $4.99 within 30 days after release. Customers can enjoy these films in HD on their Mac or PC and on their widescreen TV with Apple TV, as well as in standard definition on their iPhone or iPod with video. The iTunes Store is the world’s most popular online TV and movie store, with over 250 million TV episodes purchased and over 33 million movies purchased and rented.
Still no closed captioning however. Someday they will complete that puzzle. And the supply of HD films is extremely small. They'll get it there.
I grabbed a copy of "W." to test the quality. It's fantastic. The movie came in both HD (1280 x 544) and standard definition (853 x 362) formats, the latter for portable device use. Nice.