You're still only receiving 'all' 1080 lines at half the frequency, though... So i suppose 1080i at 60Hz would end up as 1080p at 30Hz.
Is that right?
in a way yes...and not to get way too off topic:
The actual frame rate of a 1080i broadcasts is around 0.1% slower than implied. So when you have a 1080i30 aka 30Hz transmission it really just outputs about 29.97 frames each second. Which are just 24/30/60 and 23.976/29.97/59.94
So really, there is no 1080p broadcasting in existence at this time.
digitizing film from a 35mm is at 1080p/24, fit into 1080i/50 or 1080i/60 (progressive with segmented frames). With proper 3:2 deinterlacing reversal, it can be converted back into a true 1080p/24 signal.
(various sources and books iv ebeen reading lately aswell)
So in retrospect, a 1080i or 720p HDTV is a great and still current technology for apple tv and wont notice a huge quality difference, say if appletv does start disbursing 1080p content, there will definitely be a video Pull-up of about 0.1% ~ 0.4% depending on the Hz of the signal itself.
As 1080i IS INTERLACED due to the pull-down of 1080p content and pull up of 720p material.
So yes again, the TV will work fine and perfect and will be a reasonable display for appletv =)
iam looking into a hdtv myself for my new appletv arriving soon! cant wait to spend money on movie rentals from iTunes as opposed to driving in the cold to the video store, wasting 45minutes not finding what i want and leaving with something i wont watch till the last day! lol!! @ $5 a pop
save gas + rental money!!
hope that information helped!!!