If you have a standard definition TV with a composite input, you CAN use the Apple TV, but only in black and white. Just simply connect a cable from the green (luma) component output to your yellow composite input and select 480i as the resolution for NTSC or 576i for PAL (or else it will flicker).
I mention this only for those folks (like me) who are waiting to receive their big beautiful flat-screen TV, but can't wait to try out their new Apple TV. Just recognize that this is not a long term solution - who wants to see their iPhoto collection in black and white?
A colorblind person you insensitive clod! ;-)