Last month Hulu Plus arrived in Android world, but only 6 phones were compatible. Last night they announced that four more phones have been added which all happen to be manufactured by HTC: EVO 4G, Thunderbolt, myTouch 4G, and the G2.
It is not clear why these phones were not on the first list. Many will blame fragmentation, but I think streaming services like these are just trying to make sure things are working smoothly before allowing everyone access to it. Another example is Skype video calling, which recently launched with support for only 4 devices.