Good news! Google Chrome is getting full page zoom, and it’s the default! That only leaves Safari to implement it, as IE, Firefox & Opera have had it for a while now. [1]
Full page zoom is important because it means no more mucking about with elastic layouts (em-based) or liquid layouts (%-based). That just leaves fixed layouts (based on pixels), which is good because images, videos and other media are in pixels too!
Note: I’m not saying it’s good to use pixels for font-size: properties! (Just all the other properties, like height, width, margin, padding, etc.)
[1] Update: Safari 4 (beta) has implemented full page zoom too! All major and minor browsers have implemented full page zoom. Until widespread updating of Safari 3 with 4 and (more importantly) IE 6 with 7 or 8, approx. a quarter of visitors will only have text-based zoom available to them. IE 6 users are likely not to know anything about zoom-capabilities however.