MediaMemo's Peter Kafka hears that Hulu and its three owners want to be on the iPad, but if it happens—which won't be soon—it'll mostly likely be as part of a paid subscription package to get Hulu everywhere.
Technical challenge of switching from Flash to an iPad-friendly format aside (which isn't a huge one), here's the bigger question: Would Apple allow it on the iPad as an app, since it would compete with iTunes? (Especially if Apple's pushing for their own TV subscription plan, why would they somebody else's TV subscription app on their device?) More likely, Hulu'd have to able to run completely in the browser, where there's not much Apple could do to block it. But that's ultimately trivial.