I believe this is a NEW Snow Leopard feature as I don't remember this working in Leopard. However, now lets say that I'm uploading images to a website via Safari. I click the upload button, navigate to the folder with my images in them and they are in List view. If I don't remember what they look like by name, besides switching to icon view (which is too small in many cases), I can now just hit the space bar and bring up the images in a nice sizable view and use my up and down arrow keys to navigate between them. I just did this today and again, I don't remember this working in Leopard, but it was definitely something that I've always needed.
You can never go wrong by doing the right thing.
There are two kinds of computer users: those who have lost data and those who are about to — backup your Mac!
Just tried it in Leopard and it doesn't work for me, so I believe it's new.
Professor Hubert Farnsworth: “Nothing is impossible. Not if you can imagine it. That’s what being a scientist is all about.”
Cubert J. Farnsworth: “No, that’s what being a magical elf is all about.”