Until Apple makes a netbook, I'm resigned to using an (admittedly very lovely) Dell Inspiron Mini 9, and I was really hoping the new Windows-native interface and tab system in Safari 4 would give me a little more real estate for the actual content of web pages. Alas, it was not to be; on the Dell's 1024x600 screen, I actually get a couple of pixels less space for content when I switch from Safari 3 to Safari 4. Which is disappointing.
Disappointing, that is, until you realise that it's all down to that damned Windows font smoothing. Switch it to proper (read: Mac) font smoothing, and you get another handful of pixels more height. Still, basically: it's not quite as good at getting out of your way as Chrome, though the content zooming is pretty good.