In his presentation on Wednesday, Apple CEO Steve Jobs touted the new iPad as an outstanding entertainment device, a place to watch movies and TV shows — even name-checking ABC’s hit Modern Family.

But Jobs failed to mention that perhaps the Web’s most popular means of watching long-form TV shows like Modern Family will not be available on the megahyped device.

Executives at Hulu confirmed to Mediaweek that the increasingly popular repository of long-form, ad-supported video content won’t run on an iPad. That’s because Hulu operates on Flash software, which Apple currently doesn’t support.The lack of Flash may impact the effectiveness of online advertising on the device, and the lack of Flash-powered video could seriously impede the appeal of the iPad, particularly since it’s being sold as a personal entertainment accessory. Of course, users can purchase TV shows and movies via iTunes. But the consumption of free, ad-supported video has exploded over the last four years — and such content seems like a good fit for the iPad’s large screen, which Jobs described as “gorgeous.”

Hulu reached 43.7 million unique users and streamed a record 924 million videos in November, per comScore.

Besides Hulu, other Web publishers, who asked not to be named, told Mediaweek they are concerned that their sites’ video will not translate on the device, rendering some of their most popular content irrelevant.