Well no, your enquiring about broadcasts not HD-DVD
Guys you will find the majority of broadcasters in the USA braodcast in 1080i. The only ones im aware of that dont are:
abc = 720p
Prime-time shows: According to Jim; Boston Legal; Brothers & Sisters; Day Break; Desperate Housewives; George Lopez; Grey's Anatomy; Help Me Help You; Knights of Prosperity; Lost; Men in Trees; The Nine; Six Degrees; Ugly Betty; What About Brian
Fox = 720p
Prime-time shows: 24; Bones; Celebrity Duets; Happy Hour; House; Justice; The Loop; The O.C.; Prison Break; Stacked; Standoff; Til' Death; Vanished; The War at Home
ESPN = 720p
Shows: SportsCenter; Monday Night Countdown; NFL Countdown; NFL Live; NFL Primetime; Baseball Tonight; selected episodes of SportsCentury; Playmakers; ESPN original programming; other studio shows
Sports: Monday Night Football; Sunday Night Baseball; other selected NFL, MLB, and NBA games; college football and basketball; numerous other HD sports events yearly
National Geographic = 720p
Description: HD simulcast of National Geographic Channel
These imported shows will be upscaled/altered from their original 720p 30Hz to suit skys 1080i 50Hz/25Hz. Its not a major issue but 1080i is by far the more used format and why Sky probably made the decision and cause less confusion in sticking with 1080i only.
My guess is people couldnt tell which shows were originally in 720p format and being upscaled compared to those that are 1080i originally, wouldnt you agree? 720p with its 30Hz progressive was/is meant to be better for fast action sports and 1080p is not broadcast as yet because of its massive bandwidth requirements and probably wont be for several years.
* if anything 1080p could be adopted by the internet and as already seen many 1080p trailers have appeared.