Initially, when Hulu rolled out their Plus service, it was limited to only 6 phones: Nexus One, Nexus S, HTC Inspire 4G, Motorola Droid II, Motorola Droid X, and Motorola Atrix. Now, with their newest update, four more phones were added to their support/compatible list. They are the HTC Thunderbolt, HTC EVO 4G, T-Mobile G2, and T-Mobile myTouch 4G. Here's a quote from the Hulu blog,
We’re extremely excited to offer Hulu Plus subscribers the opportunity to watch premium content on these smartphones when, how and where they want it. As we said when we initially launched, we’ll continue to work hard to support additional devices. Stay tuned for more announcements in the coming months.
Sound off in the forums if you have tried and like the service on one of the previous devices.

Source: AndroidPolice and Hulu Blog