resolution independence?

Higher resolution means everything will be smaller. There aren't all that many displays on the market that have small enough pixel size that you would need to scale the UI unless you have bad eyesight.

Resolution independence will most likely become available with OSX 10.7. This will also mean that apps have to be updated to support it properly.

 

Apple have been talking about it for at least 5 or 6 years, but so far have done very, very little to support or introduce it. As has already been said, Resolution Independence will only really become important when the pixel density of monitors becomes much higher á la the new iPhone screen. I'm sure we're at least a few years away from that stage. It would be a nice-to-have, but right now it's not really necessary.

 

It would be useful mainly for laptops because then they could put higher resolution displays in them, as seen on laptops running Win7. The 17" MBP at 1920x1200 is IMO already in that territory, I find text on it is uncomfortably small.

You can turn resolution independent scaling on in Leopard and Snow Leopard via a Terminal command but it works very poorly because most icons etc, even in Apple applications, don't scale properly so it looks like a blurry mess.