Just watched an interview over at Channel 9 talking about the Xbox360 and XP Media Centre Edition and on that they said that if you are buying a new TV for your Xbox360 (not that you need to) then you should get one that supports 720p resolution natively (this is if you are getting an flatpannel that is). From what I have read this means that the flatpannel TV won't have to convert the resolution from the 720p resolution that the Xbox360 produces to what the TV uses to display the picture in, because this sometimes produces lag and that can effect gameplay.
Plus they mention getting Dolby Surround sound with optical-in, because the Xbox360 supports optical-out for reduced signal interference on the cables to your speakers.
They also mention that the Xbox360 only supports the 'a' wifi standard because it is immune from interference. Where as all the others ('b' and 'g' for example) can be effected by electrical interference like Microwave Ovens, 'a' is more reliable.