With three weeks left until the 84th annual Academy Awards telecast, ad inventory for the show is sold out, Disney topper Bob Iger said in a first-quarter earnings conference call Tuesday afternoon.

Every year, around this time in February, ABC makes the same announcement, but it’s still reassuring to know that the telecast remains attractive to major brands. General Motors dropped out as a sponsor in 2009, when the economy was tough and the ad market was soft. But Hyundai came on that same year and remains a big spender as the only automotive sponsor. Last year, Amazon.com, Anheuser-Busch, AT&T, Best Buy, Coke, Nokia, Procter & Gamble, Sprint, Hyundai, McDonald’s also bought ad time, and they’re likely to be a part of the 2012 production. (Incidentally, the Academy signs off on all advertising and sponsors that are a part of the telecast.

The show is usually the second most expensive network TV buy, right after the Super Bowl, but the inventory available is about 40% less than a typical hour of primetime. The Academy limits the commercial time to 8-10 minutes per hour, including ABC show promos. An hour of primetime usually contains about 16 minutes of commercials and promos.

For ad buyers, the ceremony is attractive because it’s live, which means most viewers aren’t skipping through the commercials, and it’s consistently the highest-rated entertainment special of the year. It also tends to attract an educated, upscale audience.

ABC, which will celebrate its 37th year of broadcasting the show live, also plays a big role in making sure that the Academy’s buzz machine is in full gear well in advance of the ceremony, including developing an Oscar app for the iPhone and iPad and designing and maintaining oscars.com.