New Powerbooks, whatever they call them. I'm not sure I'll be able to say "MacBook Pro" without a self-conscious wince.
4x faster is a nice number - the memory bandwidth numbers (6.3x faster) are certainly impressive. I'll have to avoid using one so I don't start hating my 1.25Ghz G4.
A little disappointed that there's no massive design change - it's a bit thinner, but I'm still hoping someone will solve the core ergonomic problem of laptop screens - why can't I slide it up about six inches when I'm using it?
I love the claim that it'll be cooler and use less battery power, but I'll wait to hear what people say.
I think the killer 3rd party accessory for this will be a magnetic adapter for old power supplies - it's a nice new design, but lots of people have more than one power supply, and they're expensive to replace.