Hey Blanka,
yeah, I tried 720p 50hz and 60hz but it just looks blurry and washed out. 1080i works, but I can only get it to sync at 30hz, and it just doesn't look right. My other Hyperspin box didn't have this problem, but my newer setup with the ATi 5770 looks like garbage in all the "supported modes." I finally figured out a slight work around- I connect it using an hdmi to dvi cable (hdmi in to the TV with DVI into the video card) and Catalyst somehow auto detects it as a 1920 x 1080 display @ 60hz. But it's still not sharp and clear until I switch the desktop res through Windows7 to 1680 x 1050, and bingo it looks great! Catalyst still sees it as 1920 x 1080, but somehow Windows is scaling it in a way that fits the funky resolution of the 720p plasma. Still, I don't get why I have to do some crazy work around to get it to scale right. If an xbox, wii, and a multitude of other devices can scale perfectly to it, why can't the ATi driver see it right? I've also tried power stip and it only makes things worse. I was about ready to swap the video card out until I discovered the above work around. Anyhow, now I've got XBMC working beautifully! And I can't wait to get Hyperspin up and running- was going to wait for 2.0 to be released. Nonetheless, I do hope XBMC on Apple TV matures in the future. I'd love to get one for friends or family who don't need a full blown HTPC. And since it runs on iOS, once they get Cydia running on it, I'm sure it will be able to handle MAME4all just as well as the iPad. Could be fun to hack a wii-mote to joystick for emulators. Let me know if anyone has any luck with their Apple TV?