Ars Technica has confirmed that the new Apple TV software and features won't be coming to the old Apple TV.
We confirmed with an Apple spokesperson that the maximum HD resolution of the Apple TV is 720p, consistent with recent rumors. Additionally, there will be no software update to bring the new features to older Apple TVs. Older Apple TVs will continue to work as they have been working up to this point, and they will continue to be able to purchase movies and TV shows even though the new Apple TV is rental-only.
Though it stands to reason, given that the old Apple TV runs a variation of OS X (Tiger?) on Intel and the new one runs a variation of iOS (4.x?) on Apple A4, and Apple probably doesn't want to devote any resources to making a distinct update to a now dead system, those expecting TV rentals and Netflix support will no doubt be unhappy.
However, those who preferred to be able to sync and buy their media on-device won't be shedding any tears, or trying to avoid any updates that take those features away.
Which side are you on? And does this change anyone's mind about updating?