I think MS is just throwing a curve ball to Sony, afterall, all specifications are subject to change.
Also having hdd as an optional addon sucks, if game developers will have to develop for users without the hdd for cache, then they probably wouldn't develop the games for both.
Only other thing I could think of would be some sort of integrated flash memory that could be used for cache, there are high capacity flash memory chips available...
On the HDTV thing: great make all games support HD, but my TV only supports 480p and 1080i. But not 720p, make them all 1080i and I will be very happy
Edit: sorry double post