The monitor is the window
Leopard in my opinion is not a bold enough vision. Apple needs to figure out that the monitor is the window not the applicaiton container. Microsoft understands this, but Vista is not a complete implementation; but they much closer than I thought. Full-screen interfaces are the future of OS UI. Apple has everything they need to do it but they aren't.
Take iTunes for example. They have a full-screen mode that uses CoverFlow, but it's a useless interface and you have to go back to the GUI to do anything useful. I hate this. CoverFlow in iTunes needs to, at the very least, do what it does on the iPhone or iPod touch. But why stop there? Why not add searching, playlist management, ect. to the full-screen interface? On screen controls is an idea Apple pioneered, why are they not using it? Imagine viewing the iTunes store in full-screen.
iPhoto also has full-screen mode too. It has more useful features, but why not go all the way and make the whole app full-screen? Why not add full-screen to the finder and Safari too?
Now, add your full-screen apps to Spaces, mix in a little Core Animation, and you have a new way of interacting with the OS, a whole new UI paradigm. I really think this is where it's going, or at least where it should go.
But it needs to start with Safari. All three major browsers on Windows support full-screen viewing, but only Opera does on OS X. Opera is too buggy and imcompatible with various web sites to replace Safari. Apple needs to get with the program here. Many web sites can not really be appreciated until you view them full-screen. Apple's own web site looks fantastic in full-screen mode. Try it in Opera if you haven't yet.
I can't believe I'm going to say this, but if Apple doesn't get this soon, Vista will and will eventually be better because of it. I've been using Vista all week and you can almost get Windows out of the way and use everything in full-screen mode. The 3D flipper works seemlessly like this. It solves many of the UI issues I hate about Windows. It is almost there. They are so close.
Apple has everything they need but they are just not going for it. I'm very dissappointed at this. I'm not saying that they should replace the GUI, just add a new way of interacting with it with full-screen mode. A bold vision that simply extends what they already have.
The monitor is the window.